nyOJ基础题：蛇形填数

一遍AC
#include <stdio.h>
/*
描述
在n*n方陈里填入1,2,...,n*n,要求填成蛇形。例如n=4时方陈为：
10 11 12 1
9 16 13 2
8 15 14 3
7 6 5 4
输入
直接输入方陈的维数，即n的值。(n<=100)
输出
输出结果是蛇形方陈。
样例输入
3
样例输出
7 8 1
6 9 2
5 4 3
*/
int main(){
    int n;
    while(~scanf("%d", &n)){
        int a[n][n];
        for(int i = 0; i < n; i++)
            for(int j = 0; j < n; j++)
                a[i][j] = 0;

        int x, y, number;//循环变量+计数的number

        //预处理，填外圈
        a[0][n-1] = 1;
        for(y = 0, number = 1; y < n; y++) a[y][n-1] = number++;
        for(x = n-2; x >= 0; x--) a[n-1][x] = number++;
        for(y = n-2; y >= 0; y--) a[y][0] = number++;
        for(x = 1; x <= n-2; x++) a[0][x] = number++;

        x = 0, y = n-2;
        while(number <= n*n){
            //south 从a[0][n-2]开始
            //printf("%d~~~\n", a[x][y]);
            while((number <= (n*n)) && !a[x+1][y]) a[++x][y] = number++;
            //west
            while((number <= n*n) && !a[x][y-1]) a[x][--y] = number++;
            //north
            while((number <= n*n) && !a[x-1][y]) a[--x][y] = number++;
            //east
            while((number <= n*n) && !a[x][y+1]) a[x][++y] = number++;
        }

        //输出
        for(int i = 0; i < n; i++){
            for(int j = 0; j < n; j++){
                if(j==0) printf("%d", a[i][j]);
                else printf(" %d", a[i][j]);
            }
            puts("");
        }
    }
    return 0;
}