蓝桥杯模拟赛

复习蛇形矩阵的构造
方法一:

#include<iostream>
#include<cstring>

using namespace std;

int n,m;
int f[40][40];

int main()
{
    cin>>n>>m;
    int dx[4] = {0,1,0,-1},dy[4] = {1,0,-1,0};

    for(int d = 0,k = 1,x = 0,y = 0;k <= m * n;k++)
    {
        f[x][y] = k;
        int a = x + dx[d],b = y + dy[d];
        if(a<0||a>n-1||b<0||b>m-1||f[a][b])
        {
            d = (d + 1) % 4;
            a = x + dx[d],b = y + dy[d];
        }
        x = a,y = b;
    }

    cout<<f[19][19];
    return 0;
}

方法二:

#include<iostream>

using namespace std;

int a[40][40];

int main() {
    int t=0, x=1, y=1;
    t = a[x][y] = 1;
    while (t < 30 * 30) {
        while (y + 1 <= 30 && !a[x][y + 1]) a[x][++y] = ++t;
        while (x + 1 <= 30 && !a[x + 1][y]) a[++x][y] = ++t;
        while (y - 1 > 0 && !a[x][y - 1]) a[x][--y] = ++t;
        while (x - 1 > 0 && !a[x - 1][y]) a[--x][y] = ++t;

    }
    cout << a[20][20];
    return 0;
}