蓝桥杯 （计算路径）

 题意：7*7的矩阵，出发点和终点都是0,0 ，问有多少条路径，步数不超过12步。

 考虑的边界值不仅仅是迷宫边界，还有最少步数，所有的限制条件都要考虑

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <string>
#include <cstring>
#include <cstdlib>
#include <map>
#include <vector>
#include <set>
#include <queue>
#include <stack>
#include <cmath>
using namespace std;
#define lli long long 
#define pq priority_queue<int>
#define pql priority_queue<ll>
#define pqn priority_queue<node>
#define v vector<int>
#define vl vector<ll> 
#define read(x) scanf("%d",&x)
#define read2(x,y) scanf("%d %d",&x,&y);
#define lread(x) scanf("%lld",&x);
#define pt(x) printf("%dn",(x))
#define yes printf("YESn");
#define no printf("NOn");
#define gcd __gcd
#define out(x) cout<<x<<endl;
#define rep(j,k) for (int i = (int)(j); i <= (int)(k); i++)
#define input(k) for (int i = 1; i <= (int)(k); i++)  {scanf("%d",&a[i]) ; }
#define mem(s,t) memset(s,t,sizeof(s))
#define ok return 0;
#define TLE std::ios::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define test cout<<"     ++++++      "<<endl;
//二叉树 
#define lson rt<<1, l, m
#define rson rt<<1|1, m+1, r
//线段树
#define ls now<<1
#define rs now<<1|1 
const int inf = 1e6+5;
int vis[8][8],cnt=0,ans;
int dir[4][2] = {1,0,-1,0,0,1,0,-1};
void DFS(int x,int y)
{
    if(ans>12)  return ;
    if(x==1 && y==1 && ans>2) {cnt++;return ;}
    for(int i=0;i<4;i++)
    {
        int nx=x+dir[i][0];      int ny=y+dir[i][1];
        if(nx<1 || ny<1 || nx > 7 || ny>7 )    continue;
        if(!vis[nx][ny] )
        {
            vis[nx][ny]=1;
            ans++;
            DFS(nx,ny);
            ans--;
            vis[nx][ny]=0;
        }
    }
}

int main()
{
    mem(vis,0);
    ans=0;
    DFS(1,1);
    cout<<cnt<<endl;
}