162_FindPeakElement - a920604a/leetcode GitHub Wiki

class Solution {
public:
    int findPeakElement(vector<int>& nums) {
        // burce force
        int n = nums.size();
        if(n==1) return 0;
        for(int i=1;i<n-1; ++i){
            if(nums[i] > nums[i-1] && nums[i]>nums[i+1]) return i;
        }
        if(nums[0] >nums[1]) return 0;
        if(nums[n-1]>nums[n-2]) return n-1;
        return -1;
    }
};

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