Binary Search

class Solution {
public:
    int search(vector<int>& nums, int target) {
        int l = 0, r = nums.size() - 1;
        while (l <= r) {
            int mid = (l + r) / 2;
            if (nums[mid] == target) {
                return mid;
            }
            if (nums[mid] < target) {
                l = mid + 1;
            } else {
                r = mid - 1;
            }
        }
        return -1;
    }
};