梦工厂实验室 蛇形填数 dfs

#include<stdio.h>
int a[105][105];
int c=1,n,t=0;
void dfs(int x,int y)
{
    if(x<1||y<1||x>n||y>n){
        t++;
        return;
    }
    if(a[x][y]!=0){
        t++;
        return;
    }
    a[x][y]=c;
    c++;
    while(c<=n*n){
    if(t%4==0) dfs(x+1,y);
    else if(t%4==1) dfs(x,y-1);
    else if(t%4==2) dfs(x-1,y);  //遍历思路
    else dfs(x,y+1);
    }
}
int main()
{
    int i,j;
    scanf("%d",&n);
    dfs(1,n);
    for(i=1;i<=n;i++){
        for(j=1;j<=n;j++){
            if(j==1) printf("%d",a[i][j]);
            else printf(" %d",a[i][j]);
        }
        printf("\n");
    }
    return 0;
} 
/**************************************************************
    Problem: 1541
    User: 2016207228
    Language: C
    Result: 正确
    Time:1 ms
    Memory:1312 kb
****************************************************************/