I have seen the problem of finding the next greater element for each element in an array and it can be easily solved using monotonic stack. But can it be solved using recursion?
For the input array [4, 5, 2, 25], the next greater elements for each element are as follows.
4 --> 5
5 --> 25
2 --> 25
25 --> -1
Using stack
#include <bits/stdc++.h>
using namespace std;
void printNGE(int arr[], int n)
{
stack<int> s;
int res[n];
for (int i = n - 1; i >= 0; i--) {
if (!s.empty()) {
while (!s.empty() && s.top() <= arr[i]) {
s.pop();
}
}
res[i] = s.empty() ? -1 : s.top();
s.push(arr[i]);
}
for (int i = 0; i < n; i++)
cout << arr[i] << " --> " << res[i] << endl;
}
int main()
{
int arr[] = { 11, 13, 21, 3 };
int n = sizeof(arr) / sizeof(arr[0]);
printNGE(arr, n);
return 0;
}
long long fun(long long i,vector<long long>&v,long long par)
{
if(i==v.size())
return -1;
if(v[i]>v[par])
{
return v[i];
}
return fun(i+1,v,par);
}
void solve(long long i,vector<long long>&v,vector<long long>&ans)
{
if(i==v.size())return ;
solve(i+1,v,ans);
long long temp=fun(i+1,v,i);
ans[i]=temp;
}
vector<long long> nextLargerElement(vector<long long> v, int n)
{
vector<long long>ans(n,-1);
solve(0,v,ans);
return ans;
}
Related
Please excuse for my massy code. This was best I could do.
I have been solving leetcode Q5 for a while; however, I couldn't solve it. This is the closest answer I have got.
I think it's acting correctly in terms of showing outputs. But has a runtime error when
let s = "tscvrnsnnwjzkynzxwcltutcvvhdivtmcvwdiwnbmdyfdvdiseyxyiiurpnhuuufarbwalzysetxbaziuuywugfzzmhoessycogxgujmgvnncwacziyybryxjagesgcmqdryfbofwxhikuauulaqyiztkpgmelnoudvlobdsgharsdkzzuxouezcycsafvpmrzanrixubvojyeuhbcpkuuhkxdvldhdtpkdhpiejshrqpgsoslbkfyraqbmrwiykggdlkgvbvrficmiignctsxeqslhzonlfekxexpvnblrfatvetwasewpglimeqemdgdgmemvdsrzpgacpnrbmomngjpiklqgbbalzxiikacwwzbzapqmatqmexxqhssggsyzpnvvpmzngtljlrhrjbnxgpcjuokgxcbzxqhmitcxlzfehwfiwcmwfliedljghrvrahlcoiescsbupitckjfkrfhhfvdlweeeverrwfkujjdwtcwbbbbwctwdjjukfwrreveeewldvfhhfrkfjkctipubscseioclharvrhgjldeilfwmcwifwhefzlxctimhqxzbcxgkoujcpgxnbjrhrljltgnzmpvvnpzysggsshqxxemqtamqpazbzwwcakiixzlabbgqlkipjgnmombrnpcagpzrsdvmemgdgdmeqemilgpwesawtevtafrlbnvpxexkeflnozhlsqexstcngiimcifrvbvgkldggkyiwrmbqaryfkblsosgpqrhsjeiphdkptdhdlvdxkhuukpcbhueyjovbuxirnazrmpvfascyczeuoxuzzkdsrahgsdbolvduonlemgpktziyqaluuaukihxwfobfyrdqmcgsegajxyrbyyizcawcnnvgmjugxgocysseohmzzfguwyuuizabxtesyzlawbrafuuuhnpruiiyxyesidvdfydmbnwidwvcmtvidhvvctutlcwxznykzjwnnsnrvcst"
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int is_palindrome(char * s);
void get_substring(const char *str, char *substr, int start, int end);
char * longestPalindrome(char * s){
int strlength = strlen(s);
int end = strlength - 1;
int start = 0;
char substr[1000];
char *longstr = (char *)malloc(1000 * sizeof(char));
strcpy(longstr, "");
while (start <= end)
{
get_substring(s, substr, start, end);
// printf("%s\n", substr);
if (is_palindrome(substr) > strlen(longstr))
{
// printf("UPDATE : %s\n", substr);
strcpy(longstr, substr);
}
if (end == start)
{
start++;
end = strlength - 1;
}
else
{
end--;
}
}
// printf("LONG : %s", longstr);
return longstr;
}
void get_substring(const char *str, char *substr, int start, int end) {
int length = end - start + 1;
strncpy(substr, str + start, length);
substr[length] = '\0';
}
int is_palindrome(char * s){
int length = strlen(s);
int mid = length/2;
if (length % 2 == 0)
{
// printf("EVEN : %d\n", mid);
mid--;
int upperptr = mid+1;
int i = 0;
if (s[mid] != s[upperptr])
{
// printf("Returning FALSE [0]\n");
return 0;
}
while (mid-i >= 0 && upperptr+i <= length)
{
// printf("%c and %c and mid is %c\n", s[mid-i], s[upperptr+i], s[mid]);
if (s[mid-i] != s[upperptr+i])
{
// printf("Returning FALSE [1]\n");
return 0;
}
i++;
}
}
else
{
// printf("ODD: %d\n", mid+1);
int i = 0;
while (mid-i >= 0 && mid+i <= length)
{
// printf("%c and %c and mid is %c\n", s[mid-i], s[mid+i], s[mid]);
if (s[mid-i] != s[mid+i])
{
// printf("Returning FALSE [2]\n");
return 0;
}
i++;
}
}
// printf("Returning TRUE\n");
return length;
}
I had difficulties returning a local string. then found out that local string value can't be returned and has to be dynamically malloced and the pointer has to be returned.
So I fixed it (somehow, if it is right). But I reckon this is causing different - even harder - problems that I can't manage.
Im trying to make it where the values in my 2d array add up from diagonally top left to bottom right and top right to bottom left. I'm having trouble thinking what to do. I'm thinking maybe a for loop would be in there but thats all I think. I also have an accumulator too. My question is referring to my lefttoright and righttoleft functions. Thanks!
#include <iostream>
using namespace std;
const int COLS = 3;
bool showarray(const int[][COLS]);
int sumofrow(const int[][COLS]);
int sumofcolumn(const int[][COLS]);
int lefttoright(const int[][COLS]); // function to sum diagonally
int righttoleft(const int[][COLS]); // function to sum diagonally
int main()
{
int table1[COLS][COLS] = { 1,2,3,4,5,6,7,8,9 };
int table2[COLS][COLS] = { {4, 9, 2},
{3, 5, 7},
{8, 1, 6} };
cout << "ARRAY\n";
cout << (showarray(table1) ? " " : " NOT ");
cout << "a LO Shu Magic Square!"
<< endl;
}
int sumofrow(const int arry[][COLS])
{
int total;
for (int i = 0; i < COLS; i++)
{
total = 0;
for (int count = 0; count < COLS; count++)
{
total += arry[i][count];
}
}
return total;
}
int sumofcolumn(const int arry[][COLS])
{
int total;
for (int col = 0; col < COLS; col++)
{
total = 0;
for (int row = 0; row < COLS; row++)
{
total += arry[col][row];
}
}
return total;
}
int lefttoright(const int arry[][COLS])
{
int total = 0;
// for loop possibly?
return total;
}
int righttoleft(const int arry[][COLS])
{
int total = 0;
// for loop here possibly?
return total;
}
I got a homework where I needed to wright a program to find MST of a graph. I tried running it on the school server but I get a run-time error. On big servers like HackerEarth or HackerRank, however, I got correct answers on all test cases. The boundary for the number of edges and vertices is 100000 and for the weight of an edge 10000. Vertices are labeled from 0 to n.
Here is my code:
#include <stdio.h>
#include <algorithm>
using namespace std;
class Edge
{
public:
int x, y;
long long w;
bool operator<(const Edge& next) const;
};
bool Edge::operator<(const Edge& next) const
{
return this->w < next.w;
}
class DisjointSet
{
public:
int parent, rank;
};
DisjointSet set[100100];
Edge edges[100100];
int findWithPathCompression(int x)
{
if(set[x].parent != x)
set[x].parent = findWithPathCompression(set[x].parent);
return set[x].parent;
}
bool unionByRank(int x1, int y1)
{
int x = findWithPathCompression(x1);
int y = findWithPathCompression(y1);
if(x == y)
return false;
if(set[x].rank > set[y].rank)
set[y].parent = x;
else if(set[y].rank > set[x].rank)
set[x].parent = y;
else
{
set[y].parent = x;
set[x].rank++;
}
return true;
}
int main()
{
int n, m, e = 0, c = 0;
long long r = 0;
scanf("%d %d",&n,&m);
for(int i = 0; i <= n; i++)
{
set[i].parent = i;
set[i].rank = 1;
}
for(int i = 0; i < m; i++)
{
scanf("%d %d %lld",&edges[i].x,&edges[i].y,&edges[i].w);
edges[i].x;
edges[i].y;
}
sort(edges,edges + m);
while(e != n - 1)
{
if(unionByRank(edges[c].x,edges[c].y))
{
r += edges[c].w;
e++;
}
c++;
}
printf("%lld\n",r);
}
#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
This dynamic programming algorithm is returning unhandled exception error probably due to the two dimensional arrays that I am using for various (and very large) number of inputs. I can't seem to figure out the issue here. The complete program as follows:
// A Dynamic Programming based solution for 0-1 Knapsack problem
#include<stdio.h>
#include<stdlib.h>
#define MAX 10000
int size;
int Weight;
int p[MAX];
int w[MAX];
// A utility function that returns maximum of two integers
int maximum(int a, int b) { return (a > b) ? a : b; }
// Returns the maximum value that can be put in a knapsack of capacity W
int knapSack(int W, int wt[], int val[], int n)
{
int i, w;
int retVal;
int **K;
K = (int**)calloc(n+1, sizeof(int*));
for (i = 0; i < n + 1; ++i)
{
K[i] = (int*)calloc(W + 1, sizeof(int));
}
// Build table K[][] in bottom up manner
for (i = 0; i <= n; i++)
{
for (w = 0; w <= W; w++)
{
if (i == 0 || w == 0)
K[i][w] = 0;
else if (wt[i - 1] <= w)
K[i][w] = maximum(val[i - 1] + K[i - 1][w - wt[i - 1]], K[i - 1][w]);
else
K[i][w] = K[i - 1][w];
}
}
retVal = K[n][W];
for (i = 0; i < size + 1; i++)
free(K[i]);
free(K);
return retVal;
}
int random_in_range(unsigned int min, unsigned int max)
{
int base_random = rand();
if (RAND_MAX == base_random) return random_in_range(min, max);
int range = max - min,
remainder = RAND_MAX % range,
bucket = RAND_MAX / range;
if (base_random < RAND_MAX - remainder) {
return min + base_random / bucket;
}
else {
return random_in_range(min, max);
}
}
int main()
{
srand(time(NULL));
int val = 0;
int i, j;
//each input set is contained in an array
int batch[] = { 10, 20, 30, 40, 50, 5000, 10000 };
int sizeOfBatch = sizeof(batch) / sizeof(batch[0]);
//algorithms are called per size of the input array
for (i = 0; i < sizeOfBatch; i++){
printf("\n");
//dynamic array allocation (variable length to avoid stack overflow
//calloc is used to avoid garbage values
int *p = (int*)calloc(batch[i], sizeof(int));
int *w = (int*)calloc(batch[i], sizeof(int));
for (j = 0; j < batch[i]; j++){
p[j] = random_in_range(1, 500);
w[j] = random_in_range(1, 100);
}
size = batch[i];
Weight = batch[i] * 25;
printf("| %d ", batch[i]);
printf(" %d", knapSack(Weight, w, p, size));
free(p);
free(w);
}
_getch();
return 0;
}
Change this:
for (i = 0; i < size + 1; i++)
free(K[i]);
free(K);
return K[size][Weight];
To this:
int retVal;
...
retVal = K[size][Weight];
for (i = 0; i < size + 1; i++)
free(K[i]);
free(K);
return retVal;