标签:ext ted and should 链表 contain less space color
Given an array nums containing n + 1 integers where each integer is between 1 and n (inclusive), prove that at least one duplicate number must exist. Assume that there is only one duplicate number, find the duplicate one.
Note:
O(n2)
.解题思路:首先去这个博客瞻仰一下http://keithschwarz.com/interesting/code/?dir=find-duplicate
这题目的思路巧妙在把数组数值转化成了索引,也就是把顺序数组变成了链表来用。构造出链表图之后,就使得该题变成了带环链表找进入链表的入口值。至于构造出的图为什么一定有环,这是因为n个值,n+1个索引,由鸽笼原理可知,总有一个数被指了两次,也就是重复出现的值,也就是环的entry。
class Solution { public: int findDuplicate(vector<int>& nums) { if(nums.size()<=1)return -1; int slow=nums[0],fast=nums[nums[0]]; while(slow!=fast){ slow=nums[slow]; fast=nums[nums[fast]]; } fast=0; while(slow!=fast){ slow=nums[slow]; fast=nums[fast]; } return slow; } };
287. Find the Duplicate Number
标签:ext ted and should 链表 contain less space color
原文地址:http://www.cnblogs.com/tsunami-lj/p/6442128.html