1105 Spiral Matrix (25 分)

#include <iostream>
#include <algorithm>
#include <cmath>
using namespace std;
int a[100100], b[1010][1010];
int main(){
	int N, n, ret = 0;
	cin >> N;
	for(int i = 0; i < N; ++i)
		cin >> a[i];
	sort(a, a + N, greater<int>());
	for(n = sqrt(N); n > 0; n--)
		if(	N % n == 0)
			break;
	int m = N / n, ceng = m / 2 + m % 2;
	for(int i = 0; i < ceng; ++i){
		for(int j = i; j <= n - 1 - i && ret < N; ++j)
			b[i][j] = a[ret++];
		for(int j = i + 1; j <= m - 2 - i && ret < N; ++j)
			b[j][n - 1 - i] = a[ret++];
		for(int j = n - 1 - i; j >= i && ret < N; --j)
			b[m - 1 - i][j] = a[ret++];
		for(int j = m - 2 - i; j >= i + 1 && ret < N; --j)
			b[j][i] = a[ret++];
	}
	for(int i = 0; i < m; ++i){
		for(int j = 0; j < n; ++j){
			if(j != 0)
				cout << " ";
			cout << b[i][j]; 
		}
		cout << endl;
	}
}