PAT (Basic Level) 1050 spiral matrix

The meaning of problems

Given array, in order to fill the helical retraction matrix.

Thinking

The classic snakeskin walk title. Direct look at the code.

Code

#include <bits/stdc++.h>
using namespace std;
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cout.tie(nullptr);
	int N;
	cin >> N;
	int n, m;
	for (int i = 1; i * i <= N; ++i) {
		if (N % i == 0) {
			m = i;
			n = N / i;
		}
	}
	vector<int> a(N);
	for (int& e : a) 
		cin >> e;
	sort(a.begin(), a.end(), greater<int>());
	vector<vector<int>> ans(n, vector<int>(m, -1));
	int cnt = 0, x = 0, y = -1;
	while (cnt < N) {
		while (y + 1 < m && ans[x][y + 1] == -1) ans[x][++y] = a[cnt++];
		while (x + 1 < n && ans[x + 1][y] == -1) ans[++x][y] = a[cnt++];
		while (y - 1 >= 0 && ans[x][y - 1] == -1) ans[x][--y] = a[cnt++];
		while (x - 1 >= 0 && ans[x - 1][y] == -1) ans[--x][y] = a[cnt++];
	}
	for (auto it : ans) 
		for (int i = 0; i < it.size(); ++i) 
			cout << it[i] << (i == it.size() - 1 ? '\n' : ' ');
	return 0;
} 

HINT

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