100但是unaccepted

P1067 [NOIP2009 普及组] 多项式输出

molsonsama @ 2024-02-01 15:44:53

代码如下，hack那一项很奇怪具体错误信息为

“Wrong Answer.wrong answer On line 1 column1,read 2, expected 1.”

但是在本地运行数据的时候，结果是正确的。输入： 0 1 输出： 1

#include <iostream>
#include <sstream>
using namespace std;
int main()
{
    stringstream answer;
    int n;
    cin >> n;
    int index[n] = {0};
    for (int i = n; i >= 0; i--)
    {
        cin >> index[i];
    }
    if (n > 1){
        if (index[n] == 1)
        {
            answer << "x^" << n;
        }
        else if (index[n] == -1)
        {
            answer << "-x^" << n;
        }
        else if (index[n] != 0)
        {
            answer << index[n] << "x^" << n;
        }
    }
    for (int i = n - 1; i > 1; i--)
    {
        if (index[i] == 0)
        {
            continue;
        }
        else if (index[i] == 1)
        {
            answer << "+x^" << i;
        }
        else if (index[i] == -1)
        {
            answer << "-x^" << i;
        }
        else if (index[i] > 0)
        {
            answer << "+" << index[i] << "x^" << i;
        }
        else if (index[i] < 0)
        {
            answer << index[i] << "x^" << i;
        }
    }
    if (index[1] != 0)
    {
        if (index[1] > 1)
            answer << "+" << index[1] << "x";
        else if (index[1] < -1)
            answer << index[1] << "x";
        else if (index[1] == 1)
            answer << "+x";
        else if (index[1] == -1)
            answer << "-x";
    }
    if (index[0] != 0)
    {
        if (index[0] > 0)
            answer << "+" << index[0] << endl;
        else
            answer << index[0] << endl;
    }
    string ans = answer.str();
    if (ans[0] == '+')
        ans.erase(ans.begin());
    if(ans == "") cout << 0;
    cout << ans << endl;
    return 0;
}

by molsonsama @ 2024-02-01 15:45:31

求助，谢谢了

by ilibilib @ 2024-02-01 15:52:59

@molsonsama

#include <iostream>
#include <sstream>
using namespace std;
int index[100] = {0};
int main()
{
    stringstream answer;
    int n;
    cin >> n;
    for (int i = n; i >= 0; i--)
    {
        cin >> index[i];
    }
    if (n > 1){
        if (index[n] == 1)
        {
            answer << "x^" << n;
        }
        else if (index[n] == -1)
        {
            answer << "-x^" << n;
        }
        else if (index[n] != 0)
        {
            answer << index[n] << "x^" << n;
        }
    }
    for (int i = n - 1; i > 1; i--)
    {
        if (index[i] == 0)
        {
            continue;
        }
        else if (index[i] == 1)
        {
            answer << "+x^" << i;
        }
        else if (index[i] == -1)
        {
            answer << "-x^" << i;
        }
        else if (index[i] > 0)
        {
            answer << "+" << index[i] << "x^" << i;
        }
        else if (index[i] < 0)
        {
            answer << index[i] << "x^" << i;
        }
    }
    if (index[1] != 0)
    {
        if (index[1] > 1)
            answer << "+" << index[1] << "x";
        else if (index[1] < -1)
            answer << index[1] << "x";
        else if (index[1] == 1)
            answer << "+x";
        else if (index[1] == -1)
            answer << "-x";
    }
    if (index[0] != 0)
    {
        if (index[0] > 0)
            answer << "+" << index[0] << endl;
        else
            answer << index[0] << endl;
    }
    string ans = answer.str();
    if (ans[0] == '+')
        ans.erase(ans.begin());
    if(ans == "") cout << 0;
    cout << ans << endl;
    return 0;
}

数组开在外面

by molsonsama @ 2024-02-01 19:45:00

@ilibilib 谢谢！但是请问为什么数组在里面会导致结果错误呢？

by ilibilib @ 2024-02-01 20:02:18

@molsonsama 大概是数组是静态的，程序执行之前就要根据开的数组大小分配内存，所以数组大小必须是确定的数字，而不是在程序执行之后才决定数组大小。除非你用动态数组。

(？我不知道说得准不准确，反正差不多是这样的

by molsonsama @ 2024-02-01 20:19:20

@ilibilib 好的,谢谢!