輸出蛇形矩陣

// ConsoleApplication5.cpp : 定義控制檯應用程式的入口點。
//

#include "stdafx.h"
#include <iostream>
#include <vector>

using namespace::std ;

int main()
{
	int n;
	cin >> n;

	vector<vector<int>> vec(n, vector<int>(n, 0));
	int left = 0, right = n - 1;
	int top = 0, bottom = n - 1;
	int index = 1;

	while (index <= n * n) {
		for (int i = left; i <= right; ++i) {
			if (index > n*n)break;
			vec[top][i] = index;
			++index;
		}
		++top;
		for (int i = top; i <= bottom; ++i) {
			if (index > n*n)break;
			vec[i][right] = index;
			++index;
		}
		--right;
		for (int i = right; i >= left; --i) {
			if (index > n*n)break;
			vec[bottom][i] = index;
			++index;
		}
		--bottom;
		for (int i = bottom; i >= top; --i) {
			if (index > n*n)break;
			vec[i][left] = index;
			++index;
		}
		++left;
	}
	
	for (int i = 0; i < n; ++i) {
		for (int j = 0; j < n; ++j) {
			cout << vec[i][j] << " ";
		}
	}

	return 0;
}