LeetCode, GeeksForGeeks Problem of the day solution

class twoStacks { int *arr; int size; int top1, top2; public: twoStacks(int n=100) { size = n; arr = new int[n]; top1 = -1; top2 = size; } //Function to push an integer into the stack1. void push1(int x) { top1++; arr[top1] = x; } //Function to push an integer into the stack2. void push2(int x) { top2--; arr[top2] = x; } //Function to remove an element from top of the stack1. int pop1() { if(top1==-1){ return -1; } else{ int val = arr[top1]; top1--; return val; } } //Function to remove an element from top of the stack2. int pop2() { if(top2==size){ return -1; } else{ int val = arr[top2]; top2++; return val; } } };

class Solution { public: bool canFinish(int numCourses, vector>& prerequisites) { int n=numCourses; vector indegree(n, 0); vector> adj(n, vector()); for (auto& pre : prerequisites) { int u = pre[1]; int v = pre[0]; indegree[v]++; adj[u].push_back(v); } queueq; for(int i=0; ians; while(!q.empty()){ int node=q.front(); q.pop(); ans.push_back(node); for(auto it:adj[node]){ indegree[it]--; if(indegree[it]==0) q.push(it); } } if(ans.size()!=n) return 0; else return 1; } };

class Solution { public: bool isFrequencyUnique(int n, int arr[]) { unordered_map mp; set st; for(int i=0;i

class Solution{ public: vector eventualSafeNodes(vector>& G) { int N = G.size(); vector> R(N); vector outdegree(N), safe(N), ans; queue q; for (int i = 0; i < N; ++i) { for (int v : G[i]) { R[v].push_back(i); } outdegree[i] = G[i].size(); if (outdegree[i] == 0) q.push(i); } while (q.size()) { int u = q.front(); q.pop(); safe[u] = 1; for (int v : R[u]) { if (--outdegree[v] == 0) q.push(v); } } for (int i = 0; i < N; ++i) { if (safe[i]) ans.push_back(i); } return ans; } };

class Solution{ public: //You need to complete this fucntion #define mod 1000000007 long long power(long long a,long long b){ long long ans=1; while(b){ if(b & 1) ans=(ans*a)%mod; a=(a*a)%mod; b>>=1; } return ans; } long long power(int N,int R) { return (power(N,R)%mod); } };

class Solution { public: void markParents(TreeNode* root, unordered_map& parent_track){ queue q2; q2.push(root); while(!q2.empty()){ TreeNode* temp = q2.front(); q2.pop(); if(temp->left){ parent_track[temp->left] = temp; q2.push(temp->left); } if(temp->right){ parent_track[temp->right] = temp; q2.push(temp->right); } } } vector distanceK(TreeNode* root, TreeNode* target, int k) { unordered_map parent_track; markParents(root, parent_track); unordered_map vis; queue q; q.push(target); vis[target] = true; int dist=0; while(!q.empty()){ int size = q.size(); if(dist == k){ break; } dist++; for(int i=0;ileft && !vis[node->left]){ q.push(node->left); vis[node->left] = true; } if(node->right && !vis[node->right]){ q.push(node->right); vis[node->right] = true; } if(parent_track[node] && !vis[parent_track[node]]){ q.push(parent_track[node]); vis[parent_track[node]] = true; } } } vector ans; while(!q.empty()){ TreeNode* temp=q.front(); q.pop(); ans.push_back(temp->val); } return ans; } };

class Solution { public: /*You are required to complete this method*/ int findK(int a[MAX][MAX],int n,int m,int k) { vectorans; int rowStart =0; int rowEnd = n-1; int colStart = 0; int colEnd = m-1; while(rowStart <= rowEnd && colStart<=colEnd){ //left to right for(int i=colStart; i<=colEnd; i++){ ans.push_back(a[rowStart][i]); } rowStart++; //top to bottom for(int i=rowStart; i<=rowEnd; i++){ ans.push_back(a[i][colEnd]); } colEnd--; if(rowStart<=rowEnd){ for(int i=colEnd; i>=colStart; i--){ ans.push_back(a[rowEnd][i]); } rowEnd--; } if(colStart <= colEnd){ for(int i=rowEnd; i>=rowStart; i--){ ans.push_back(a[i][colStart]); } colStart++; } } return ans[k-1]; } };

class Solution { public: int minDepth(TreeNode* root) { if(root==NULL){ return 0; } if(root->left==NULL && root->right==NULL){ return 1; } int leftST = 1e9; if(root->left){ leftST = minDepth(root->left); } int rightST = 1e9; if(root->right){ rightST = minDepth(root->right); } return 1+min(leftST, rightST); } };

class Solution { public: //Function to find transpose of a matrix. void transpose(vector >& matrix, int n) { for(int i=0;i

class Solution { public: int largestVariance(string s) { vectorarr(26); for(auto w:s){ arr[w-'a']++; } int ans=0; for(char i='a';i<='z';i++){ for(char j='a';j<='z';j++){ if(j==i or arr[i-'a']==0 or arr[j-'a']==0) continue; for(int k=1;k<=2;k++){ int c1=0; int c2=0; for(auto w:s){ if(w==i) c1++; if(w==j) c2++; if(c2>c1){ c1=0; c2=0; } if(c1>0&&c2>0) ans=max(ans,c1-c2); } reverse(s.begin(),s.end()); } } } return ans; } };