2018年東北農業大學春季校賽-wyh的吃雞

BFS:

1. 從起點開始BFS，遇到X點則return；

2. vis[px][py][0]表明通過pxpy這點前尚未找到車； 

　vis[px][py][1]表明通過pxpy這點前已經找到車； 

3. ip記錄是否找到車；

 　d表示方向

4. 最後判斷時間是否超時；

5. 簡單的BFS，結束！

#include<iostream> #include<cstdio> #include<cstring> #include<algorithm> #include<map> #include<queue> #include<set> #include<string> #include<cmath>
#define test printf("***\n")
#define ka getchar();getchar()
#define ka1 getchar()
#define iis std::ios::sync_with_stdio(false)
using namespace std; typedef long long LL; const int N = 110; const int INF = 0x3f3f3f3f; const int mod = 1e9 + 7; const double eps = 1e-8; struct lp { int x, y,d,ip,step; friend bool operator <(const lp &a,const lp &b){ if(a.step!=b.step)return a.step>b.step; return a.ip<b.ip; } } now, t; int n, k; char ar[N][N]; int dir[4][2] = {1, 0, -1, 0, 0, 1, 0, -1}; bool vis[N][N][10]; int bfs(int a, int b) { priority_queue<lp>Q; memset(vis,0,sizeof(vis)); t.x = a; t.y = b; t.d = -1;t.ip=0; t.step=0; Q.push(t); vis[a][b][0]=1; while(!Q.empty()) { t = Q.top(); Q.pop(); for(int i = 0; i < 4; ++i) { int px = t.x + dir[i][0], py = dir[i][1] + t.y; if(px < 0 || py < 0 || px >= n || py >= n)continue; if(ar[px][py] == 'O')continue; if(t.step>k)return 0; if(t.ip == 0) { if(vis[px][py][0])continue; if(t.d != -1 && t.d != i)continue; if(t.d != -1) { now.d = -1;now.ip=0; now.x = px; now.y = py; vis[px][py][0]=1; now.step = t.step + 1; if(ar[px][py]=='X')return now.step; if(ar[px][py]=='C'){ now.ip=1; vis[px][py][1]=1; } Q.push(now); } else { now.d = i;now.ip=0; now.x = t.x; now.y = t.y; now.step = t.step + 1; Q.push(now); } }else{ if(vis[px][py][1])continue; now.d = i;now.ip=1; now.x = px; now.y = py; now.step = t.step + 1; if(ar[px][py]=='X')return now.step; vis[px][py][1]=1; Q.push(now); } } } return 0; } int main() { int t; scanf("%d", &t); while(t--) { int a, b; scanf("%d%d", &n, &k); for(int i = 0; i < n; ++i) { scanf("%s", &ar[i]); for(int j = 0; j < n; ++j) { if(ar[i][j] == 'S')a = i, b = j; } } int ans = bfs(a, b); if(ans!=0&&ans<=k) { printf("YES\n%d\n", ans); } else { printf("NO\n"); } } return 0; } /* 3 2 3 .X S. 2 3 .X SC 2 4 .X S. */

View Code

 題目：

https://www.nowcoder.com/acm/contest/93/H