binary_search.cpp

static const int __ = []() {
  std::ios::sync_with_stdio(false);
  std::cin.tie(NULL);
  std::cout.tie(NULL);
  return 0;
}();
class Solution {
public:
  // void binarysearch(int &low, int &high, vector<int>& nums, int &target){
  //     int mid = low + (high-low)/2;
  //     if(target==nums[mid]){
  //         return;
  //     }
  //     else if(target<nums[mid]){
  //         high = mid;
  //         binarysearch(low,high,nums,target);
  //     }
  //     else{
  //         low = mid;
  //         binarysearch(low,high,nums,target);
  //     }
  // }
  int search(vector<int> &nums, int target) {
    int n = nums.size();
    int low = 0;
    int high = n - 1;
    int mid;
    while (low <= high) {
      mid = low + (high - low) / 2;
      if (nums[mid] == target) {
        return mid;
      } else if (target < nums[mid]) {
        high = mid - 1;
      } else {
        low = mid + 1;
      }
    }
    // int index;
    // binarysearch(low,high,nums,target);
    // index = low + (high-low)/2;
    return -1;
  }
};