LeetCode-C#实现-二分查找(#162/704）

162. Find Peak Element

山脉数组的峰顶索引

public class Solution {
    public int FindPeakElement(int[] nums) {
        int low=0,mid=0,high=nums.Length-1;
        while(low<high){
            mid=(low+high)/2;
            if(nums[mid]>nums[mid+1])high=mid;
            else low=mid+1;
        }
        return low;
    }
}

 

704. Binary Search

二分查找

public class Solution {
    public int Search(int[] nums, int target) {
        int low=0,mid=0,high=nums.Length-1;
        while(low<high){
            mid=low+(high-low)/2;//防溢出
            //不判断相等，使low，mid，high不断向target的索引靠近
            if(nums[mid]<target) low=mid+1;
            else high=mid;
        }
        //若存在返回三者任一皆可，否则返回-1
        return nums[low]==target?low:-1;
    }
}