c++算法题解法的不解之处

Question

题目是这样的

#include <iostream>
#include <vector>
#include <string>
#include <sstream>
#include <stdlib.h> 
using namespace std;

int toBinary(int m);

int main()
{
    int n = 1; //所输入的行数
    cin >> n;
    vector<string> str;
    vector<string>::iterator itor;
    for (int i = 0;i < n;i++) {
        string input_num;
        cin >> input_num;
        str.insert(str.end(),input_num);
    }

    for (itor = str.begin();itor != str.end();++itor) {
        string str_num = *itor;
        int int_num = atoi(str_num.c_str());
        int sec_num = toBinary(int_num);
        //int sec_num = bitset<sizeof(int) * 8>(int_num);
        ostringstream stream;
        stream << sec_num;
        string sec_str = stream.str();
        //string sec_str = to_string(sec_num);
        vector<char> sec_char;
        vector<char>::iterator itr;
        sec_char.resize(sec_str.size());
        sec_char.assign(sec_str.begin(), sec_str.end());
        //const char *sec_char = sec_str.c_str();
        int count = 0;
        for (itr = sec_char.begin();itr != sec_char.end();++itr) {
            char res_num = *itr;
            if (res_num == '1') {
                count++;
            }
        }
        cout << count << endl;

    }
    return 0;
}

//二进制转换函数(反)
int toBinary(int m)
{
    int a;
    string b;
    string c = "";
    while (m != 0) {
        a = m % 2;
        ostringstream d;
        d << a;
        b = d.str();
        //b = to_string(a);
        c = c + b;
        m = m >> 1;
    }

    return atoi(c.c_str());
}

我自己本地各种试，结果都符合预期。但是在ACM系统提交时，得到的反馈是wronganswer,我是不是有特殊情况没考虑到？实在不解。

Answer 1

组数(1<N<1000)
整数(0<=M<=10000)

题目对输入有限定，没找到代码中有对这个进行判断。

如果对您有帮助，请采纳答案好吗，谢谢！