剑指offer 面试题03. 数组中重复的数字

题目描述

https://leetcode-cn.com/problems/shu-zu-zhong-zhong-fu-de-shu-zi-lcof/

参考

https://www.acwing.com/problem/content/video/14/

复杂度

时间：n
空间：1

代码

class Solution {
public:
    int findRepeatNumber(vector<int>& nums) {
        int val=-1;
        int n=nums.size();
        for(int i=0;i<n;i++){
            val=nums[i];
            while(val!=i){
                if(val==nums[val]){
                    return val;
                }
                swap(nums[i],nums[val]);
                val=nums[i];
            }
        }
        return -1;
    }
};