题解 | #寻找峰值#

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param nums int整型一维数组 
     * @return int整型
     */
    
    public static int index = -1;
    public int findPeakElement (int[] nums) {
        // write code here
        int first = 0, rear = nums.length-1;
        if(nums.length == 0){
            return -1;
        }
        if(nums.length == 1){
            return 0;
        }
        if(nums[0]>nums[1]){
            return 0;
        }
        if(nums[nums.length-1]>nums[nums.length-2]){
            return nums.length-1;
        }
        binarySearch(nums,1,nums.length-2);
        return index;
        
    }
    public void binarySearch(int[] nums,int first,int rear){
        if(first > rear || first ==0 || rear == nums.length-1){
            return;
        }
        int mid = (first + rear) / 2;
        if(nums[mid]>nums[mid-1] && nums[mid]>nums[mid+1]){
            index = mid;
            return;
        }
        binarySearch(nums,first,mid-1);
        binarySearch(nums,mid+1,rear);
        
    }
}