数组中重复数字时间复杂度O(N)，空间复杂度O(1)【C++】

#include <iostream>

bool duplicate(int numbers[], int length, int * duplication){
    if(numbers == nullptr || length <= 0){
        return false;
    }
    for(int i = 0;i < length;i ++){
        if(numbers[i] < 0 || numbers[i] > length - 1)
            return false;
    }
    for(int i = 0;i < length;i ++){
        while(numbers[i] != i){
            if(numbers[i] == numbers[numbers[i]]){
                * duplication = numbers[i];
                return true;
            }
            int temp = numbers[i];
            numbers[i] = numbers[temp];
            numbers[temp] = temp;
        }
    }
    return false;
}

int main(int argc, const char * argv[]) {
    int numbers[] = {3, 1, 2, 0, 2, 5, 3};
    int dup;
    if(duplicate(numbers, 7, & dup)){
        std::cout << dup << std::endl;
    }
}