Unable to figure out what is causing the buffer overflow in below code. I reckon it has to do with the vector but I am guarding against out of bounds access. Is there anything else that could be causing the overflow?
class Solution {
public:
bool canPartition(vector<int>& nums) {
int sum = 0;
bool canPartition = true;
vector<vector<int>> dp(nums.size(), vector<int>(sum / 2 + 1, -1));
sum = accumulate(nums.begin(),nums.end(),0);
if (sum % 2 != 0)
{
canPartition = false;
}
if (true == canPartition)
{
canPartition = canPartitionRecursive(nums, 0, sum/2, dp);
}
return canPartition;
}
bool canPartitionRecursive(vector<int>& nums, int index, int sum,
vector<vector<int>>& dp)
{
if (sum == 0)
{
return true;
}
if (index >= nums.size() || sum < 0)
{
return false;
}
if (dp[index][sum] != -1)
{
if (true == canPartitionRecursive(nums, index+1, sum - nums[index],dp))
{
dp[index][sum] = 1;
return true;
}
dp[index][sum] = canPartitionRecursive(nums, index + 1, sum, dp);
}
return dp[index][sum] = 1? true:false;
}
};
This looks like a transpositional error (all subvector will have size 1):
int sum = 0;
vector<vector<int>> dp(nums.size(), vector<int>(sum / 2 + 1, -1));
sum = accumulate(nums.begin(),nums.end(),0);
Perhaps calculation of sum should be moved before dp initialization?
help please, at Arduino Uno I receive a signal from the sensor and build a graph using processing 2.2.1, but you need to scale up without losing proportions. My attempts failed, the proportion was crumbling(I tried to multiply the values) Code:
Serial myPort;
int xPos = 1;
int yPos = 100;
float yOld = 0;
float yNew = 0;
float inByte = 0;
int lastS = 0;
PFont f;
void setup () {
size(1200, 500);
println(Serial.list());
myPort = new Serial(this, Serial.list()[0], 9600);
myPort.bufferUntil('\n');
background(0xff);
}
void draw () {
int s = second();
PFont f = createFont("Arial",9,false);
textFont(f,9);
fill(0);
if (s != lastS){
stroke(0xcc, 0xcc, 0xcc);
line(xPos, yPos+10, xPos, yPos+30);
text(s + " Sec.", xPos+5, yPos+30);
lastS = s;
}
}
void mousePressed(){
save(lastS + "-heart.jpg");
}
void serialEvent (Serial myPort) {
String inString = myPort.readStringUntil('\n');
if (inString != null) {
inString = trim(inString);
if (inString.equals("!")) {
stroke(0, 0, 0xff); // blue
inByte = 1023;
} else {
stroke(0xff, 0, 0); //Set stroke to red ( R, G, B)
inByte = float(inString);
}
inByte = map(inByte, 0, 1023, 0, height);
yNew = inByte;
line(xPos-1, yPos-yOld, xPos, yPos-yNew);
yOld = yNew;
if (xPos >= width) {
xPos = 1;
yPos+=200;
if (yPos > height-200){
xPos = 1;
yPos=100;
background(0xff);
}
} else {
xPos++;
}
}
}
There are multiple ways to scale graphics.
A simple method to try is to simply scale() the rendering (drawing coordinate system).
Bare in mind currently the buffer is only cleared when the xPos reaches the right hand side of the screen.
The value from Arduino is mapped to Processing here:
inByte = map(inByte, 0, 1023, 0, height);
yNew = inByte;
you should try to map change height to a different value as you see fit.
This however will scale only the Y value. The x value is incremented here:
xPos++;
you might want to change this increment to a different value that works with the proportion you are trying maintain between x and y.
I want to keep my QMainWindow always inside of the desktop, so I add the implementation for QMainWindow::moveEvent :
void MainWindow::moveEvent(QMoveEvent *ev)
{
if(ev->pos().x() < 0) setGeometry(0, ev->oldPos().y(), width(), height());
}
But when I move the window to out of desktop left bounding, the app is crashed.
What is wrong with this code? Why it is crashed? Is my solution correct?
//--Update:
I tried with this:
int newx = ev->pos().x(),
newy = ev->pos().y();
if(ev->pos().x() < 0) newx = 0;
if(ev->pos().y() < 0) newy = 0;
move(newx, newy);
It worked without crash but I'm not satisfied because of the moving is not smooth.
This should smoothly help with the upper left corner .. but you'll need to add some more conditions to get it working for all four sides.
posX and posY are member variables.
void MainWindow::moveStep() { // [SLOT]
int movX = 0, movY = 0;
if(posX < 0) movX = 1;
if(posY < 0) movY = 1;
move(posX + movX, posY + movY);
}
void MainWindow::moveEvent(QMoveEvent *ev) {
if(ev->pos().x() < 0 || ev->pos().y() < 0) {
posX = ev->pos().x();
posY = ev->pos().y();
QTimer::singleShot(10, this, SLOT(moveStep()));
}
}
To have it even more elegantly consider using QVariantAnimation with a QRect and setGeometry().
I'm trying to make a program that will use the readings it gets from a distance sensor to control the attributes of circles (size, xy and colour). To do this I'm trying to make it record the current value and apply that to the value when you press the relevant key (Eg. press 's' and it changes the size to whatever the distance was at that point). - Ideally I'd like the circle to change whatever field is next dynamically as you move your hand over the sensor, but that seems a bit beyond me.
I've tried to do as much as I can, but everything I'm not sure of I've commented out. Any tips or advice? I'm really not sure what I'm doing when it comes to classes and constructors.
EDIT: When I run the code, nothing happens.
import processing.serial.*;
int xpos, ypos, s, r, g, b;
Circle circle;
int shapeSize, distance;
String comPortString;
Serial myPort;
void setup(){
size(displayWidth,displayHeight); //Use entire screen size.
//Open the serial port for communication with the Arduino
myPort = new Serial(this, "/dev/cu.usbmodem1411", 9600);
myPort.bufferUntil('\n'); // Trigger a SerialEvent on new line
}
void draw(){
background(0);
delay(50); //Delay used to refresh screen
println(distance);
}
void serialEvent(Serial cPort){
comPortString = (new String(cPort.readBytesUntil('\n')));
if(comPortString != null) {
comPortString=trim(comPortString);
/* Use the distance received by the Arduino to modify the y position
of the first square (others will follow). Should match the
code settings on the Arduino. In this case 200 is the maximum
distance expected. The distance is then mapped to a value
between 1 and the height of your screen */
distance = int(map(Integer.parseInt(comPortString),1,200,1,height));
if(distance<0){
/*If computer receives a negative number (-1), then the
sensor is reporting an "out of range" error. Convert all
of these to a distance of 0. */
distance = 0;
}
}
}
void keyPressed()
{
// N for new circle (and keep old one)
if((key == 'N') || (key == 'n')) {
println("n");
circle = new Circle(1,1,1,1,1,1);
}
//r - change red
if((key == 'R') || (key == 'r')) {
float red = map(distance, 0, 700, 0, 255);
r = int(red);
println("r " + r);
}
//g - change green
if((key == 'G') || (key == 'g')) {
float green = map(distance, 0, 700, 0, 255);
g = int(green);
println("g " + g);
}
//b - change blue
if((key == 'B') || (key == 'b')) {
float blue = map(distance, 0, 700, 0, 255);
b = int(blue);
println("b " + b);
}
//S - change Size
if((key == 'S') || (key == 's')) {
s = distance;
println("s " + s);
}
//X - change x pos
if((key == 'X') || (key == 'x')) {
xpos = distance;
println("x " + xpos);
}
//y - change y pos
if((key == 'Y') || (key == 'y')) {
ypos = distance;
println("y " + ypos);
}
}
class Circle {
Circle(int xpos, int ypos, int s, int r, int g, int b){
ellipse(xpos, ypos, s, s);
color(r, g, b);
}
int getX(){
return xpos;
}
int getY(){
return ypos;
}
}
I would split this into steps/tasks:
Connecting to the Arduino
Reading values from Arduino
Mapping read values
Controlling mapping
You've got the Arduino part pretty much there, but things look messy when trying to map read values to the circle on screen.
For now, for simplicity reasons, let's ignore classes and focus on simply drawing a single ellipse with x,y,size,r,g,b properties.
To get read of jitter you should update the property ellipse continuously, not just when pressing a key. On the key event you should simply change what property gets updated.
You could use extra variables to keep track of what ellipse properties you're updating.
Here's a refactored version of the code based on the points above:
import processing.serial.*;
int xpos,ypos,s,r,g,b;
int distance;
int propertyID = 0;//keep track of what property should be updated on distance
int PROP_XPOS = 0;
int PROP_YPOS = 1;
int PROP_S = 2;
int PROP_R = 3;
int PROP_G = 4;
int PROP_B = 5;
void setup(){
size(400,400);
//setup some defaults to see something on screen
xpos = ypos = 200;
s = 20;
r = g = b = 127;
//initialize arduino - search for port based on OSX name
String[] portNames = Serial.list();
for(int i = 0 ; i < portNames.length; i++){
if(portNames[i].contains("usbmodem")){
try{
Serial arduino = new Serial(this,portNames[i],9600);
arduino.bufferUntil('\n');
return;
}catch(Exception e){
showSerialError();
}
}
}
showSerialError();
}
void showSerialError(){
System.err.println("Error connecting to Arduino!\nPlease check the USB port");
}
void draw(){
background(0);
fill(r,g,b);
ellipse(xpos,ypos,s,s);
}
void serialEvent(Serial arduino){
String rawString = arduino.readString();//fetch raw string
if(rawString != null){
String trimmedString = rawString.trim();//trim the raw string
int rawDistance = int(trimmedString);//convert to integer
distance = (int)map(rawDistance,1,200,1,height);
updatePropsOnDistance();//continously update circle properties
}
}
void updatePropsOnDistance(){
if(propertyID == PROP_XPOS) xpos = distance;
if(propertyID == PROP_YPOS) ypos = distance;
if(propertyID == PROP_S) s = distance;
if(propertyID == PROP_R) r = distance;
if(propertyID == PROP_G) g = distance;
if(propertyID == PROP_B) b = distance;
}
void keyReleased(){//only change what proprty changes on key press
if(key == 'x' || key == 'X') propertyID = PROP_XPOS;
if(key == 'y' || key == 'Y') propertyID = PROP_YPOS;
if(key == 's' || key == 'S') propertyID = PROP_S;
if(key == 'r' || key == 'R') propertyID = PROP_R;
if(key == 'g' || key == 'G') propertyID = PROP_G;
if(key == 'b' || key == 'B') propertyID = PROP_B;
}
//usually a good idea to test - in this case use mouseY instead of distance sensor
void mouseDragged(){
distance = mouseY;
updatePropsOnDistance();
}
If this makes sense, it can easily be encapsulated in a class.
We could use an array to store those properties, but if something like props[0] for x, props1 for y, etc. is harder to read, you could use an IntDict which allows you to index values based on a String instead of a value (so you can do props["x"] instead of props[0]).
Here's an encapsulated version of the code:
import processing.serial.*;
Circle circle = new Circle();
void setup(){
size(400,400);
//initialize arduino - search for port based on OSX name
String[] portNames = Serial.list();
for(int i = 0 ; i < portNames.length; i++){
if(portNames[i].contains("usbmodem")){
try{
Serial arduino = new Serial(this,portNames[i],9600);
arduino.bufferUntil('\n');
return;
}catch(Exception e){
showSerialError();
}
}
}
showSerialError();
}
void showSerialError(){
System.err.println("Error connecting to Arduino!\nPlease check the USB port");
}
void draw(){
background(0);
circle.draw();
}
void serialEvent(Serial arduino){
String rawString = arduino.readString();
if(rawString != null){
String trimmedString = rawString.trim();
int rawDistance = int(trimmedString);
int distance = (int)map(rawDistance,1,200,1,height);
circle.update(distance);
}
}
void keyReleased(){
circle.setUpdateProperty(key+"");//update the circle property based on what key gets pressed. the +"" is a quick way to make a String from the char
}
//usually a good idea to test - in this case use mouseY instead of distance sensor
void mouseDragged(){
circle.update(mouseY);
}
class Circle{
//an IntDict (integer dictionary) is an associative array where instead of accessing values by an integer index (e.g. array[0]
//you access them by a String index (e.g. array["name"])
IntDict properties = new IntDict();
String updateProperty = "x";//property to update
Circle(){
//defaults
properties.set("x",200);
properties.set("y",200);
properties.set("s",20);
properties.set("r",127);
properties.set("g",127);
properties.set("b",127);
}
void draw(){
fill(properties.get("r"),properties.get("g"),properties.get("b"));
ellipse(properties.get("x"),properties.get("y"),properties.get("s"),properties.get("s"));
}
void setUpdateProperty(String prop){
if(properties.hasKey(prop)) updateProperty = prop;
else{
println("circle does not contain property: " + prop+"\navailable properties:");
println(properties.keyArray());
}
}
void update(int value){
properties.set(updateProperty,value);
}
}
In both examples you can test the distance value by dragging your mouse on the Y axis.
Regarding the HC-SR04 sensor, you can find code on the Arduino Playground to get the distance in cm. I haven't used the sensor myself yet, but I notice other people has some issues with it, so it's worth checking this post as well. If you want to roll your own Arduino code, no problem, you can use the HC-SR04 datasheet(pdf link) to get the formula:
Formula: uS / 58 = centimeters or uS / 148 =inch; or: the range = high
level time * velocity (340M/S) / 2; we suggest to use over 60ms
measurement cycle, in order to prevent trigger signal to the echo
signal.
It's important to get accurate values (you'll avoid jitter when using these to draw in Processing). Additionally you can use easing or a moving average.
Here's a basic moving average example:
int historySize = 25;//remember a number of past values
int[] x = new int[historySize];
int[] y = new int[historySize];
void setup(){
size(400,400);
background(255);
noFill();
}
void draw(){
//draw original trails in red
stroke(192,0,0,127);
ellipse(mouseX,mouseY,10,10);
//compute moving average
float avgX = average(x,mouseX);
float avgY = average(y,mouseY);
//draw moving average in green
stroke(0,192,0,127);
ellipse(avgX,avgY,10,10);
}
void mouseReleased(){
background(255);
}
float average(int[] values,int newValue){
//shift elements by 1, from the last to the 2nd: count backwards
float total = 0;
int size = values.length;
for(int i = size-1; i > 0; i--){//count backwards
values[i] = values[i-1];//copy previous value into current
total += values[i];//add values to total
}
values[0] = newValue;//add the newest value at the start of the list
total += values[0];//add the latest value to the total
return (float)total/size;//return the average
}
I have a custom line item which is subclassed from QGraphicsLineItem. When mouse move event occurs on the line item edge, I rotate or resize the line accordingly. My problem is that before perfroming rotation or resizing, the line item exists in local coordinate system with P1(0,0) and P2(x,y).
When P2 is used as anchor for resizing and rotating and mouse is placed on P1, the P1 takes the mouse event->pos() cordinates. Once the resize is done, I need to transform the line item to a local coordinate system. How do I do that? I tried using setTransformOriginPoint(event->pos()) but it doesnt translate my P1 to origin.
The code used for rotation/resize is as follows:
void CustomGraphicsLineItem::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
{
qDebug()<<"Line mouse move event";
if( dragIndex != -1 )
{
const QPointF anchor = dragIndex == 0 ? this->line().p1() : this->line().p2();
this->setLine(dragIndex == 0 ? QLineF(anchor, event->pos()) : QLineF(event->pos(),anchor));
}
if(dragIndex == 1)
{
this->setTransformOriginPoint(event->pos());
}
this->update();
}
void CustomGraphicsLineItem::mousePressEvent(QGraphicsSceneMouseEvent *event)
{
qDebug()<<"Line mouse press event";
// initialPos = mapToScene(event->pos());
dragIndex = -1;
const QPointF event_pos = event->pos();
const qreal l1 = QLineF( event_pos, this->line().p1() ).length();
const qreal l2 = QLineF( event_pos, this->line().p2() ).length();
//threshold indicates the area of influence of the mouse click event, which is set to 5.0 pixels
const qreal threshold = 15.0;
if(l1 < threshold || l2 < threshold)
{
if( l1 < l2 && l1 < threshold )
{
dragIndex = 1;
}
else if ( l2 < l1 && l2 < threshold )
{
dragIndex = 0;
}
else
{
dragIndex = -1;
}
event->setAccepted( dragIndex != -1 );
}
//if we click anywhere other than the end points, then consider it to be a drag
if(l1 > threshold && l2 > threshold)
{
QMimeData * mimeData = new QMimeData;
CustomGraphicsLineItem * item = this;
QByteArray byteArray(reinterpret_cast<char*>(&item),sizeof(CustomGraphicsLineItem*));
mimeData->setData("Item",byteArray);
// start the event
QDrag * drag = new QDrag(event->widget());
drag->setMimeData(mimeData);
drag->exec();
dragStart = event->pos();
event->accept();
}
}
void CustomGraphicsLineItem::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
{
dragIndex = -1;
QGraphicsLineItem::mouseReleaseEvent(event);
}
void CustomGraphicsLineItem::paint (QPainter *painter, const QStyleOptionGraphicsItem *, QWidget *)
{
// qDebug() << "CustomGraphicsLineItem::paint called ";
QPen pen=QPen();
pen.setColor(Qt::red);
pen.setWidth(5);
painter->setPen(pen);
painter->setBrush(Qt::red);
painter->setRenderHint(QPainter::Antialiasing);
painter->drawLine(line());
}