704. Binary Search

Given an array of integers nums which is sorted in ascending order, and an integer target, write a function to search target in nums. If target exists, then return its index. Otherwise, return -1.

You must write an algorithm with O(log n) runtime complexity.

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