题解 | #寻找峰值#

二分查找思路

public int solve (int[] a) {
        // write code here
        if(a== null || a.length == 0) return 0;
        int ans = Integer.MIN_VALUE;
        for(int i = 0;i < a.length-1;++i){
            int low = i,high = a.length-1;//要留出两个数字，所以low最大是a.length-2
             while(low < high){
                int mid = low + (high-low)/2;
                if(a[mid] < a[mid+1]){
                    low = mid+1;
                }else{
                    high = mid;
                }
            }
            ans = Math.max(ans,low);
        }
        return ans;
    }