找出数组中的重复数字

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

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