704.Binary Search

题目描述

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.

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

我的解法

实现代码

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class Solution {
public:

int search(vector<int>& nums, int target) {
int left = 0;
int right= nums.size()-1;
while(left <= right){
int mid = (right - left) / 2 + left;
if (nums[mid] == target)
return mid;
if (nums[mid] < target)
left = mid + 1;
if (nums[mid] > target)
right = mid - 1;
}
return -1;
}
};