C++ 代码
class Solution {
public:
int duplicateInArray(vector<int>& nums) {
int n = nums.size();
for (int x : nums)
if (x < 0 || x >= n)
return -1;
for (int i = 0; i < n; i ++ ) {
for(int j=i+1;j<n;j++)
{
if(nums[i]==nums[j])return nums[i];
}
}
return -1;
}
};