LeetCode, GeeksForGeeks Problem of the day solution

class Solution { public: int pivotInteger(int n) { int left = 2; int right= n-1; if (n < 2) return n; int leftSum = 1; int rightSum = n; int totalSum = (n * (n + 1)) /2; while(leftSum < totalSum && rightSum < totalSum && left < right){ if (leftSum < rightSum){ leftSum += left; left++; }else{ rightSum += right; right--; } } if (leftSum == rightSum) return left; else return -1; } };

class Solution{ public: vector matrixDiagonally(vector>&mat) { int n=mat.size(); vector ans(n*n,0); int k=0; bool up=true; int r=0,c=0; while(r0 && c0 && r

class Solution { public: ListNode* removeZeroSumSublists(ListNode* head) { ListNode* dummy = new ListNode(0), *cur = dummy; dummy->next = head; int prefix = 0; map m; while (cur) { prefix += cur->val; if (m.count(prefix)) { cur = m[prefix]->next; int p = prefix + cur->val; while (p != prefix) { m.erase(p); cur = cur->next; p += cur->val; } m[prefix]->next = cur->next; } else { m[prefix] = cur; } cur = cur->next; } return dummy->next; } };

class Solution { private: vector> mat; vector> res; void multiply(vector>& res, const vector>& mat, long long m) { vector> res1(3, vector(3, 0)); for (int i = 0; i < 3; ++i) { for (int j = 0; j < 3; ++j) { for (int k = 0; k < 3; ++k) { res1[i][j] += (res[i][k] * mat[k][j]) % m; res1[i][j] %= m; } } } for (int i = 0; i < 3; ++i) { for (int j = 0; j < 3; ++j) { res[i][j] = res1[i][j]; } } } void matrixExponentiation(long long n, long long m) { while (n > 0) { if (n & 1) { multiply(res, mat, m); } multiply(mat, mat, m); n /= 2; } } public: long long genFibNum(long long a, long long b, long long c, long long n, long long m) { res = vector>(3, vector(3, 0)); res[0][0] = res[1][1] = res[2][2] = 1; mat = vector>(3, vector(3, 0)); mat[0][0] = a; mat[0][1] = b; mat[0][2] = mat[1][0] = mat[2][2] = 1; mat[1][1] = mat[1][2] = mat[2][0] = mat[2][1] = 0; if (n <= 2) { return 1 % m; } else { matrixExponentiation(n - 2, m); return (res[0][0] + res[0][1] + c * res[0][2]) % m; } } };

class Solution { public: string customSortString(string order, string s) { string ret = ""; for (char c : order) { for (size_t i = 0U; i < s.size(); ++i) { if (c == s[i]) { ret += s[i]; s[i] = ';'; } } } for (char c : s) { if (c != ';') ret += c; } return ret; } };

class Solution{ public: bool check(vector> &mat2, int n, int x){ int i = 0; int j = n-1; while(i >= 0 && i < n && j >= 0 && j < n){ if(mat2[i][j] == x){ return true; } else if(mat2[i][j] < x){ i++; } else j--; } return false; } int countPairs(vector> &mat1, vector> &mat2, int n, int x) { // Your code goes here int cnt = 0; for(int i = 0;i < n;i++){ for(int j = 0;j < n;j++){ int c = x - mat1[i][j]; if(check(mat2,n,c)){ cnt++; } } } return cnt; } };

class Solution { public: vector intersection(vector& a1, vector& a2) { set s1(a1.begin(), a1.end()); set s2(a2.begin(), a2.end()); set s; set_intersection(s1.begin(), s1.end(), s2.begin(), s2.end(), inserter(s, s.begin())); vector res(s.begin(), s.end()); return res; } };

class Solution{ public: string removeDuplicates(string str) { vector v1(26,0),v2(26,0); string s=""; for(char& ch:str){ if(ch>='A'&&ch<='Z'){ if(v1[ch-'A']==0){ s.push_back(ch); } v1[ch-'A']++; } if(ch>='a'&&ch<='z'){ if(v2[ch-'a']==0){ s.push_back(ch); } v2[ch-'a']++; } } return s; } };

class Solution { public: int getCommon(vector& nums1, vector& nums2) { int i=0, j=0; int m = nums1.size(); int n = nums2.size(); while(inums2[j]){ j++; } else{ i++; } } return -1; } };

class Solution{ public: char nthCharacter(string s, int r, int n) { string temp = s; for (int i = 0;i < r; i++) { string ans = ""; for (auto j :temp) { if (j == '1') ans += "10"; else ans += "01"; if (ans.size()>n) break; } temp = ans; } return temp[n]; } };