双层循环

class Solution {
public:
// Parameters:
// numbers: an array of integers
// length: the length of array numbers
// duplication: (Output) the duplicated number in the array number
// Return value: true if the input is valid, and there are some duplications in the array number
// otherwise false
bool duplicate(int numbers[], int length, int* duplication) {
if(length<=0) return false;
for(int i=0;i<length;i++)//循环遍历每一个数
{
for(int j=i+1;j<length;j++)//循环遍历判断第i个数后面是否有和第i个数相同的
{
if(numbers[i]==numbers[j])
{
*duplication=numbers[i];
return true;
}
}
}
return false;
}
};