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FindPeakElement.java
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25 lines (24 loc) · 899 Bytes
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/**
* https://leetcode.com/articles/find-peak-element/
*/
public class FindPeakElement {
/**
* 首先局部峰值有很多
* 1，如果nums[mid]>nums[mid+1]，说明当前递减，左边肯定有个峰值，因为如果
* 没有，则意味着往左走会不停地上升，走到头的时候因为是负无穷，所以也相当于峰值
* 右边不一定有峰值，因为可能一直是下降趋势
* 2，如果nums[mid]<nums[mid+1]，说明当前是上升趋势，右边肯定有个峰值，理由同上
* 3，题目说了不存在nums[i]=nums[i+1]的情况
*/
public int findPeakElement(int[] nums) {
int l = 0, r = nums.length - 1;
while (l < r) {
int mid = (l + r) / 2;
if (nums[mid] > nums[mid + 1])
r = mid;
else
l = mid + 1;
}
return l;
}
}