蛇形矩阵

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<vector>
#include<string>
#include<stack>
#define N 30005
#define PINF 0x7fffffff
#define NINF 0
#define MAX(a,b) (a<b?a:b)
using namespace std;
int a[100][100];
int main()
{
int n,i,j,cnt,n_sq,low_bound,up_bound;

cin>>n;
n_sq = n * n; //多少个数
cnt = 1;      //计数器
i = j = 0;    //初始坐标
up_bound = n - 1;   //上界
low_bound = 0;      //下界
while(cnt <= n_sq)
{
for(j;j<=up_bound;j++)
a[i][j] = cnt++;
j--; i++;
for(i;i<=up_bound;i++)
a[i][j] = cnt++;
i--; j--;
for(j;j>=low_bound;j--)
a[i][j] = cnt++;
j++; i--;
for(i;i>low_bound;i--)
a[i][j] = cnt++;
i++; j++;
up_bound--;
low_bound++;
}

for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
printf("%-3d ",a[i][j]);    //占3位 向左对齐
cout<<endl;
}

return 0;
}

while(cnt <= n_sq)
{
for(j;j<=up_bound;j++)
a[i][j] = cnt++;
j--; i++;