704. Binary Search.cpp

Given a sorted (in ascending order) integer array nums of n elements and a target value, write a function to search target in nums. If target exists, then return its index, otherwise return -1.


Example 1:

Input: nums = [-1,0,3,5,9,12], target = 9
Output: 4
Explanation: 9 exists in nums and its index is 4

Example 2:

Input: nums = [-1,0,3,5,9,12], target = 2
Output: -1
Explanation: 2 does not exist in nums so return -1


Note:

You may assume that all elements in nums are unique.
n will be in the range [1, 10000].
The value of each element in nums will be in the range [-9999, 9999].






class Solution {
public:
    int search(vector<int>& nums, int target) {
        int start=0, end=nums.size()-1;

        while(start<=end){
            int mid=start+(end-start)/2;
            if(nums[mid]==target) return mid;
            else if(nums[mid]>target) end=mid-1;
            else start=mid+1;
        }
        return -1;
    }
};