I was solving problem timusOJ Metro. I solved it using DP but I am getting TLE. I don't know how to do it better? Solution in Ideone. Help!
#include <bits/stdc++.h>
using namespace std;
double dis[1005][1005];
map< pair< int, int >, int > m;
int N, M, K;
double min( double a, double b ){
if( a < b )
return a;
return b;
}
int main(){
cin >> M >> N;
cin >> K;
dis[0][0]= 0;
for( int i= 1; i<= N; ++i )
dis[i][0]= 100*i;
for( int j= 1; j<= M; ++j )
dis[0][j]= 100*j;
for( int i= 0, x,y; i< K; ++i ){
scanf( "%d%d", &x, &y );
m[{y,x}]++;
}
double shortcut= sqrt(20000);
for( int i= 1; i<= N; ++i )
for( int j= 1; j<= M; ++j ){
//cout << i << " " << j << "\n\t";
if( m[{i,j}] > 0 ){
dis[i][j]= min( dis[i-1][j-1] + shortcut , min(
dis[i-1][j] , dis[i][j-1] ) + 100 ) ;
m[{i,j}]--;
}else{
dis[i][j]= min( dis[i-1][j], dis[i][j-1] ) + 100;
}
}
cout << ceil(dis[N][M]) << endl;
}
P.S. I have problem in formatting code in this platform therefore ideone is used.
UPD: Accepted :)
Read the question wrong , I claim that by triangular inequality The distance to go to a block diagonally is lesser than travelling right and up.!
I will submit and explain soon..
Related
I'm testing a piece of my code, which is shown below:
#include <Rcpp.h>
using namespace Rcpp;
// [[Rcpp::export]]
NumericMatrix testOutMat(const int& ncols, const int& nrows, const NumericVector& col_prob){
//Store row and column positions
NumericVector col_pos = no_init(nrows);
NumericVector row_pos = no_init(nrows);
int row_val;
int nz_counter=0;
for(int j=0; j<ncols; ++j){
for(int i=0; i<nrows; ++i){
row_val = R::rbinom(1,col_prob[j]);
Rcout << "i,j: " << i << "," << j << std::endl;
Rcout << "val: " << row_val << std::endl;
if(row_val==1){ //if (i,j)th entry is a 1, save location
row_pos[i] = i;
col_pos[i] = j;
nz_counter += 1;
} else{ //assign as NA
row_pos[i] = NA_REAL;
col_pos[i] = NA_REAL;
}
Rcout << "row_pos[i]: " << row_pos[i] << std::endl;
Rcout << "col_pos[i]: " << col_pos[i] << std::endl;
Rcout << "num non-zeros: " << nz_counter << std::endl;
}
}
NumericMatrix out = no_init(nz_counter,2);
Rcout << "Printing output matrix" << std::endl;
for(int i=0; i<nz_counter; ++i){
if(!Rcpp::NumericVector::is_na(row_pos[i])){
out(i,0) = row_pos[i];
out(i,1) = col_pos[i];
}
Rcout << "row_pos[i]: " << row_pos[i] << std::endl;
Rcout << "col_pos[i]: " << col_pos[i] << std::endl;
}
return out;
}
/*** R
set.seed(1)
res <- testOutMat(ncols=5,nrows=5,col_prob = runif(20, 0.1, 0.2))
*/
From the output, I have that the entries (i,j)={(0,0),(3,1)} are non-zero, so that res should be a 2x2 matrix with 0 0 in the first row and 3 1 in the second. However, I get something very different:
[,1] [,2]
[1,] 64 1024
[2,] 1 4
I suspect that this is due to how I'm handling NAs. The overall goal of the function is to generate the row and column indices for non-zero elements (generated by the call to rbinom).
I've tried debugging this for some time now and I can't seem to get a fix.
The problem here is that you're writing over row_pos and col_pos over and over again (ncols times) without any kind of keeping track of the prior result. That, coupled with your no_init() use, is what's causing the end result you see. We can change your code just a bit to ensure that row_pos and col_pos don't get overwritten:
#include <Rcpp.h>
using namespace Rcpp;
// [[Rcpp::export]]
IntegerMatrix testOutMat(const int ncols, const int nrows,
const NumericVector& col_prob) {
IntegerMatrix binomial_deviates(nrows, ncols);
IntegerVector row_positions;
IntegerVector col_positions;
int nz_counter = 0;
for ( int j = 0; j < ncols; ++j ) {
binomial_deviates(_, j) = rbinom(nrows, 1, col_prob[j]);
for ( int i = 0; i < nrows; ++i ) {
if ( binomial_deviates(i, j) == 1 ) {
row_positions.push_back(i);
col_positions.push_back(j);
nz_counter += 1;
}
}
}
IntegerMatrix out(nz_counter, 2);
for ( int i = 0; i < nz_counter; ++i ) {
out(i, 0) = row_positions[i];
out(i, 1) = col_positions[i];
}
return out;
}
/*** R
set.seed(1)
res <- testOutMat(ncols=5,nrows=5,col_prob = runif(20, 0.1, 0.2))
*/
Result:
> set.seed(1)
> res <- testOutMat(ncols=5,nrows=5,col_prob = runif(20, 0.1, 0.2))
> res
[,1] [,2]
[1,] 0 0
[2,] 3 1
I made a prim's algorithm but whenever i try to use the code it give me the same matrix back. In general it isn't minimizing. Can anyone check the code and let me know why it isn't minimizing my matrix
#include <iostream>
#include <stdlib.h>
#include <time.h>
#include <vector>
#include <list>
#include <cstdlib>
#include <iomanip>
#include <limits.h>
int minKey(int n,int key[], bool mst[])
{
// Initialize min value
int min = INT_MAX, min_index;
for (int i = 0; i < n; i++)
if (mst[i] == false && key[i] < min)
min = key[i], min_index = i;
return min_index;
}
void print(int n,int **matrix)
{
for(int i=0; i<n; i++)
{
for(int j=0; j<n; j++) // print the matrix
{
cout << setw(2) << matrix[i][j] << " ";
}
cout << endl;
}
}
int **gen_random_graph(int n)
{
srand(time(0));
int **adj_matrix = new int*[n];
for(int i = 0; i < n; i++)
{
for (int j = i; j < n; j++) //generating a N x N matrix based on the # of vertex input
{
adj_matrix[i] = new int[n];
}
}
for(int u = 0; u < n; u++)
{
for (int v = u; v < n; v++) //decide whether it has an edge or not
{
bool edgeOrNot = rand() % 2;
adj_matrix[u][v] = adj_matrix[v][u] = edgeOrNot;
cout << u << " " << v << " " << adj_matrix[u][v] << endl;
if(adj_matrix[u][v] == true)
{
adj_matrix[v][u] = true;
if(u == v) //We can't have i = j in an undirected graph
{
adj_matrix[u][v] = -1;
}
cout << u << " " << v << " " << adj_matrix[u][v] << endl;
}
else
{
adj_matrix[v][u] = adj_matrix[u][v] = -1;
cout << u << " " << v << " " << adj_matrix[u][v] << "else" << endl;
}
}
}
for(int i = 0; i < n; i++)
{
for(int j = i; j < n; j++) //create the N x N with edges and sets the weight between the edge randomly
{
if(adj_matrix[i][j] == true)
{
int weight = rand() % 10 + 1;
adj_matrix[i][j] = adj_matrix[j][i] = weight;
cout << " ( " << i << "," << j << " ) " << "weight: " << adj_matrix[i][j] << endl;
}
}
}
print(n,adj_matrix);
return (adj_matrix);
}
void solve_mst_prim_matrix(int n, int **matrix)
{
int parent[n]; // Array to store constructed MST
int key[n]; // Key values used to pick minimum weight edge in cut
bool mstSet[n]; // To represent set of vertices not yet included in MST
// Initialize all keys as INFINITE
for (int i = 0; i < n; i++)
{
key[i] = INT_MAX, mstSet[i] = false;
}
// Always include first 1st vertex in MST.
key[0] = 0; // Make key 0 so that this vertex is picked as first vertex
parent[0] = -1; // First node is always root of MST
// The MST will have n vertices
for (int count = 0; count < n-1; count++)
{
// Pick the minimum key vertex from the set of vertices
// not yet included in MST
int u = minKey(n,key, mstSet);
// Add the picked vertex to the MST Set
mstSet[u] = true;
// Update key value and parent index of the adjacent vertices of
// the picked vertex. Consider only those vertices which are not yet
// included in MST
for (int v = 0; v < n; v++)
// matrix[u][v] is non zero only for adjacent vertices of m
// mstSet[v] is false for vertices not yet included in MST
// Update the key only if matrix[u][v] is smaller than key[v]
if (matrix[u][v] && mstSet[v] == false && matrix[u][v] < key[v])
parent[v] = u, key[v] = matrix[u][v];
}
cout << endl;
print(n,matrix);
}
int main()
{
int N;
cout << "Enter number of vertices" << endl;
cin >> N;
int **matrix = gen_random_graph(N);
solve_mst_prim_matrix(N, matrix);
return 0;
}
Correct me if I'm wrong, but after reading your code, you did not even change any value of **matrix in your solve_mst_prim_matrix function. So it basically prints the same thing..
#include <iostream>
#include <vector>
#include <string>
using namespace std;
void step_selection_sort(vector <int> &a, int size, int idx){
int i,j,min,temp;
i = idx;
min = i;
for (j=i+1;j<size;j++)
{
if (a[min]>a[j])
min=j;
}
if (min!=i)
{
temp = a[i];
a[i] = a[min];
a[min] = temp;
}
idx++;
}
void selection_sort(vector <int> &a, int size, int idx){
int i;
for(i=0;i<size;i++)
{
step_selection_sort(a,size,idx);
}
}
void step_desc_sort(vector <int>& a, int size, int idx){
int i,j,max,temp;
i = idx;
max = i;
for (j=i+1;j<size;j++)
{
if (a[max]<a[j])
max=j;
}
if (max!=i)
{
temp = a[i];
a[i] = a[max];
a[max] = temp;
}
idx++;
}
void desc_sort(vector <int>& a, int size, int idx){
int i;
for(i=0;i<size;i++)
{
step_desc_sort(a,size,idx);
}
}
void swap (int & a, int & b)
{
int t = a;
a = b;
b = t;
}
int findCeil (vector <int>& nums, int first, int begin, int end)
{
int ceilIndex = begin;
for (int i = begin+1; i <= end; i++)
if (nums[i] > first && nums[i] < nums[ceilIndex])
ceilIndex = i;
return ceilIndex;
}
int findBottom(vector <int>& nums,int first,int begin,int end)
{
int bottomIndex = begin;
for (int i = begin+1; i <= end; i++)
if (nums[i] < first && nums[i] > nums[bottomIndex])
bottomIndex = i;
return bottomIndex;
}
void sortedPermutations_ASC (vector <int> nums,int num)
{
bool isfinished=false;
if(isfinished==false)
for(int i=0;i<num;i++)
cout << nums[i]; //bad access when giving inputs bigger than 8
cout << endl;
int k;
for ( k = num - 2; k >= 0; --k )
if (nums[k] < nums[k+1])
break;
if ( k == -1 )
isfinished=true;
else
{
int ceilIndex = findCeil( nums, nums[k], k + 1, num - 1 );
swap( nums[k], nums[ceilIndex] );
selection_sort(nums,num,k+1);
sortedPermutations_ASC(nums,num);
}
}
void sortedPermutations_DESC (vector <int> nums,int num)
{
int i;
bool isfinished=false;
if(isfinished==false)
for(i=0;i<num;i++)
cout << nums[i];
cout << endl;
int k;
for ( k = num - 2; k >= 0; --k )
if (nums[k] > nums[k+1])
break;
if ( k == -1 )
isfinished=true;
else
{
int bottomIndex = findBottom( nums, nums[k], k + 1, num - 1 );
swap( nums[k], nums[bottomIndex] );
desc_sort(nums,num,k+1);
sortedPermutations_DESC(nums,num);
}
return;
}
int main(){
vector <int> nums;
string line,temp;
int num,j,k;
getline(cin,line);
while(j<line.size() && line[j]!=' ')
j++;
num=stoi(line.substr(0,j));
string kind;
j++;
kind=line.substr(j);
if(kind=="ASC"){
for(k=0;k<num;k++)
nums.push_back(k+1);
sortedPermutations_ASC(nums,num);
}
if(kind=="DESC"){
for(k=0;k<num;k++)
nums.push_back(num-k);
sortedPermutations_DESC(nums,num);
}
return 0;
}
here's is my code. it gives the permutations of a number.It works properly when inputs are between 1 and 8 .But it doesn't work with numbers bigger than 8 .
for example if I give
9 ASC (it means in Ascending order)
to the program , I get "Segmentation Fault:11" in terminal (mac) after printing some of the permutations .
I tried running it in Xcode . with the same input it says :
Thread 1:EXC_BAD_ACCESS(code=2,address=0x7ffff5f3fffc8)
for the line that I put comment in front of it .
I don't know what to do anymore ...
Any help would be appreciated - thanks in advance
So I'm trying to access matrix elements via a pointer. Here is my code:
CvMat *Q = cvCreateMat(3,3, CV_32F);
for(int i = 0; i < Q->rows ; i++){
float *ptr = (float *)(Q->data.ptr + i * Q->step );
for(int j = 0; j < Q->cols ; j++){
*ptr = 0.0;
if((i ==0)&&(j==0)) *ptr = 1;
if((i ==0)&&(j==1)) *ptr = 2;
if((i ==0)&&(j==2)) *ptr = 3;
if((i ==1)&&(j==0)) *ptr = 4;
if((i ==1)&&(j==1)) *ptr = 5;
if((i ==1)&&(j==2)) *ptr = 6;
if((i ==2)&&(j==0)) *ptr = 7;
if((i ==2)&&(j==1)) *ptr = 8;
if((i ==2)&&(j==2)) *ptr = 9;
//cout << *ptr << endl;
//system("pause");
}
}
cout << CV_MAT_ELEM(*Q,float,0,0) << endl;
cout << CV_MAT_ELEM(*Q,float,0,1) << endl;
cout << CV_MAT_ELEM(*Q,float,0,2) << endl;
cout << CV_MAT_ELEM(*Q,float,1,0) << endl;
cout << CV_MAT_ELEM(*Q,float,1,1) << endl;
cout << CV_MAT_ELEM(*Q,float,1,2) << endl;
cout << CV_MAT_ELEM(*Q,float,2,0) << endl;
cout << CV_MAT_ELEM(*Q,float,2,1) << endl;
cout << CV_MAT_ELEM(*Q,float,2,2) << endl;
system("pause");
I am trying to make the matrix in the for loop as:
[1 2 3
4 5 6
7 8 9],
but when cout'ing them, I get:
3
-4.31602e+008
-4.31602e+008
6
-4.31602e+008
-4.31602e+008
9
-4.31602e+008
-4.31602e+008
Where is the -4.31602e+008 coming from? What am I not understanding here? I'm a little new to pointers.
Check out the API for CvMat (also you might want to consider using Mat if you can use c++).
I'm not totally sure what you are trying to accomplish here, but if you want to access the data using the pointer you are doing it slightly wrong at this point.
float *ptr = (float *)(Q->data.ptr + i * Q->step );
The step here is the number of bytes in a row (so here it would be 12, 4 bytes per element * 3 elements) the pointer will automatically step the correct number of bytes based on the datatype of the pointer when you do arithmetic with it (Good tutorial here). In order to access it like an array you should do it like this:
CvMat *Q = cvCreateMat(3,3, CV_32F);
for(int i = 0; i < Q->rows ; i++){
for(int j = 0; j < Q->cols ; j++){
float *ptr = (float *)(Q->data.ptr) + i*Q->rows + j; //Index is row major
if((i ==0)&&(j==0)) *ptr = 1;
if((i ==0)&&(j==1)) *ptr = 2;
if((i ==0)&&(j==2)) *ptr = 3;
if((i ==1)&&(j==0)) *ptr = 4;
if((i ==1)&&(j==1)) *ptr = 5;
if((i ==1)&&(j==2)) *ptr = 6;
if((i ==2)&&(j==0)) *ptr = 7;
if((i ==2)&&(j==1)) *ptr = 8;
if((i ==2)&&(j==2)) *ptr = 9;
}
}
A much simpler solution would be to use the CV_MAT_ELEM macro that exists.
CvMat *Q = cvCreateMat(3,3, CV_32F);
for(int i = 0; i < Q->rows ; i++){
for(int j = 0; j < Q->cols ; j++){
CV_MAT_ELEM(*Q, float, i, j) = i*Q->rows + j + 1;
}
}
You should increment ptr inside your inner j loop.
#include <iostream>
#include <vector>
int main()
{
std::vector<std::vector<double> > DV; //2d vector
std::vector<double>temp(8,0.0); //1d vector
temp[0] = 1;
temp[1] = 2;
temp[2] = 3;
temp[3] = 4;
temp[4] = 5;
temp[5] = 6;
temp[6] = 7;
temp[7] = 8;
DV.resize(3, temp);
for (int i = 0; i < DV.size(); i++)
{
for (int j = 0; j < DV.size(); j++)
{
std::cout << DV[i][j];
}
}
std::cin.get();
}
The convertion actually works but it does not give the expected the result. The output should be:
1 2 3
4 5 6
7 8
and it outputs:
123123123
Thanks in advance
I'm not aware of a method to automagically turn a 1D vector into a 2D one. It's not too hard to do manually, though...
typedef std::vector<std::vector<double>> DoubleVector2D;
DoubleVector2D boxed(size_t cols, std::vector<double> values) {
DoubleVector2D result;
for (std::size_t i = 0; i < values.size(); ++i) {
if (i % cols == 0) result.resize(result.size() + 1);
result[i / cols].push_back(values[i]);
}
return result;
}
With that done, you can call boxed(3, temp) to get back a vector of vectors of doubles. At that point, you just have to loop over them.
for (auto row : DV) {
for (auto value : row) {
std::cout << value << ' ';
}
std::cout << "\n";
}
If you're stuck without decent C++11 support, you may need to use counters or iterators.
for (int row = 0; row < DV.size(); ++row) {
for (int col = 0; col < DV[i].size(); ++col) {
std::cout << DV[row][col] << ' ';
}
std::cout << '\n';
}
Change this lines
for (int i = 0; i < DV.size(); i++){
for (int j = 0; j < DV.size(); j++){
std::cout << DV[i][j] << ", ";
}
std::cout << std::endl;
}
Your issue is how you are printing your values to the standard output.