首页 > 代码库 > find the peak value
find the peak value
A peak element is an element that is greater than its neighbors.
Given an input array where num[i] ≠ num[i+1], find a peak element and return its index.
The array may contain multiple peaks, in that case return the index to any one of the peaks is fine.
You may imagine that num[-1] = num[n] = -∞.
For example, in array [1, 2, 3, 1], 3 is a peak element and your function should return the index number 2.
计算一个数组的峰值，最简单的方法就是扫描数组，判断如果 中间值 > 左边值 && 中间值 > 右边值 那么我们就可以获取到该索引数值。算法的时间复杂度为O(n),代码如下所示：
public class Solution { public int findPeakElement(int[] num) { if(num.length== 1 ){ return 0; }else if(num.length ==2){ return (num[0] > num[1]? 0:1); }else{ for(int i = 1;i<num.length-1;i++){ if(num[i] > num[i-1] && num[i] > num[i+1]){ return i; } } return (num[num.length-1] > num[0]? (num.length-1):0); } }}我们尝试用二分法来解决这个问题，三个数无外乎四种情况，升序排列、降序排列、凸排列，凹排列。
public class Solution { public int findPeakElement(int[] num) { return binarySearckPeakElement(0,num.length-1,num); } public int binarySearckPeakElement(int left,int right,int[]num){ int mid =(right + left)/2; int value = http://www.mamicode.com/num[mid];>时间复杂度为O(nlogn)
find the peak value
声明：以上内容来自用户投稿及互联网公开渠道收集整理发布，本网站不拥有所有权，未作人工编辑处理，也不承担相关法律责任，若内容有误或涉及侵权可进行投诉： 投诉/举报 工作人员会在5个工作日内联系你，一经查实，本站将立刻删除涉嫌侵权内容。