PAT 1050 螺旋矩阵 （25 分）

#include<iostream>
#include<algorithm>
#include<cmath>
#include<vector>
using namespace std;
int main() {
    int a[10000];
    int N, m, n;
    cin >> N;
    for (int i = sqrt(N) + 1; i > 0; i--)
        if (N%i == 0) {
            m = i; n = N / i; break;
        }
    if (m < n)  swap(m, n);    //保证m>n;
    vector<vector<int>>b(m + 1);   //使用vector创建二维动态数组（第1行第1列为了方便理解不使用）
    for (int i = 0; i <= m; i++)
        b[i].resize(n + 1);
    for (int i = 0; i < N; i++)
        cin >> a[i];
    sort(a, a + N, greater<int>());    //降序排序
    int i = 1, j = 0, count = 0;
    while (N!=count) {
        while (j < n&&b[i][j + 1] == 0) b[i][++j] = a[count++];
        while (i < m&&b[i + 1][j] == 0)b[++i][j] = a[count++];
        while (j > 1 && b[i][j - 1] == 0)b[i][--j] = a[count++];
        while (i > 1 && b[i - 1][j] == 0)b[--i][j] = a[count++];
    }
    for (int i = 1; i <= m; i++) {
        cout << b[i][1];
        for (int j = 2; j <= n; j++)
            cout << " " << b[i][j];
          cout << endl;
    }
    return 0;
}