INFO It’s an Algorithm to permute string. Usefull to find all the possible permutations EXAMPLE Steps Create a function which take the string, the first index and the last index: If start and end index are the same, end of the algorithm (print or return depends on what you wants) Otherwise, loop on each index between start and end: Swap string at index start and string at index i of loop Call the function with as first index the first index + 1 Swap again string at index start and string at index i of loop Code #include <iostream> #include <string> void backtrack(std::string &s, int idx, int N) { if (idx == N) std::cout << s << std::endl; else { for (int i = idx; i <= N; i++) { std::swap(s[idx], s[i]); backtrack(s, idx + 1, N); // Reset std::swap(s[idx], s[i]); } } } int main(int ac, char *av[]) { std::string s = "ABC"; int n = s.

INFO Binary Search called “Recherche Dichotomique” in French is a searching algorithm used in a sorted array by repeatedly dividing the search interval in half. APPROACH Find the Exact Value class Solution { public: int search(vector<int> &nums, int target) { int leftPtr = 0; int rightPtr = nums.size() - 1; while (leftPtr <= rightPtr) { int m = (leftPtr + rightPtr) / 2; if (nums[m] == target) return m; else if (nums[m] < target) leftPtr = m + 1; else rightPtr = m - 1; } return -1; } }; Find Upper bound class Solution { public: int search(vector<int> &nums, int target) { int leftPtr = 0; int rightPtr = nums.

Logically, a bit-to-bit operation is a calculation manipulating the data directly at the level of the bits, according to a Boolean arithmetic Use in Programming Advanced to be blazingly fast OPERATORS