35.搜索插入位置+825.山脉数组的峰顶索引（二分查找的应用）

一、搜索插入位置

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

            mid = (left+right)/2;
        }
        return left;
    }
};

二、825.山脉数组的峰顶索引

class Solution {
public:
    int peakIndexInMountainArray(vector<int>& arr) {
        int left = 0;
        int right = arr.size()-1;
        int mid = (left+right)/2;
        while(left<right)
        {
            if(arr[mid-1]>arr[mid])
            {
                right = mid;
                 mid = (left+right)/2;
            }
            else if(arr[mid]<arr[mid+1])
            {
                left = mid;
                 mid = (left+right)/2;
            }
            else{
                return mid;
            }
        }
        return left;
    }
};