PAT甲级1105

1105 Spiral Matrix （25 分）

This time your job is to fill a sequence of N positive integers into a spiral matrix in non-increasing order. A spiral matrix is filled in from the first element at the upper-left corner, then move in a clockwise spiral. The matrix has m rows and n columns, where m and n satisfy the following: m×n must be equal to N; m≥n; and m−n is the minimum of all the possible values.

Input Specification:

Each input file contains one test case. For each case, the first line gives a positive integer N. Then the next line contains N positive integers to be filled into the spiral matrix. All the numbers are no more than 10​4​​. The numbers in a line are separated by spaces.

Output Specification:

For each test case, output the resulting matrix in m lines, each contains n numbers. There must be exactly 1 space between two adjacent numbers, and no extra space at the end of each line.

Sample Input:

12
37 76 20 98 76 42 53 95 60 81 58 93

Sample Output:

98 95 93
42 37 81
53 20 76
58 60 76

#include<bits/stdc++.h>
using namespace std;

bool cmp(int a, int b){
	return a > b;
}

int main(){
	int N, num[10010];
	scanf("%d", &N);
	for(int i = 0; i < N; i++)
		scanf("%d", &num[i]);
	sort(num, num + N, cmp);
	int m, n;
	m = sqrt(N);
	if(N / m != m)
		m=m+1;
	for(int i = m; i <= N; i++)
	if(N % i == 0){
		m = i;
		break;
	}
	n = N / m;
/*	if(n == 1){
		for(int i = 0; i < m; i++)
			printf("%d\n", num[i]);
		return 0;
	}*/
	int left = 0, right = n, up = 1, down = m;
	int matrix[110][110], sum = 0;
	while(sum < N){
		int i, j;
		i = j = left;
		while(j < right){
			matrix[i][j++] = num[sum++];
		}
		if(sum == N)
			break;
		j--;
		i++;
		while(i < down){
			matrix[i++][j] = num[sum++];
		}
		if(sum == N)
			break;
		i--;
		j--;
		while(j >= left){
			matrix[i][j--] = num[sum++];
		}
		if(sum == N)
			break;
		j++;
		i--;
		while(i >= up){
			matrix[i--][j] = num[sum++];
		}
		if(sum == N)
			break;
		left++;
		right--;
		up++;
		down--;
	}
	for(int i = 0; i < m; i++){
		for(int j = 0; j < n; j++){
			if(j != n-1)
				printf("%d ", matrix[i][j]);
			else
				printf("%d\n", matrix[i][j]);
		}
	}
	return 0;
}