2018年东北农业大学春季校赛-wyh的吃鸡

BFS:

1. 从起点开始BFS，遇到X点则return；

2. vis[px][py][0]代表经过pxpy这点前还没有找到车；

　vis[px][py][1]代表经过pxpy这点前已经找到车；

3. ip记录是否找到车；

　d表示方向

4. 最后判断时间是否超时；

5. 简单的BFS，结束！

#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 = ;
const int INF = 0x3f3f3f3f;
const int mod = 1e9 + ;
const double eps = 1e-;
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[][] = {, , -, , , , , -};
bool vis[N][N][];
int bfs(int a, int b)
{
    priority_queue<lp>Q;
    memset(vis,,sizeof(vis));
    t.x = a; t.y = b;
    t.d = -;t.ip=;
    t.step=;
    Q.push(t);
    vis[a][b][]=;
    while(!Q.empty()) {
        t = Q.top(); Q.pop();
        for(int i = ; i < ; ++i) {
            int px = t.x + dir[i][], py = dir[i][] + t.y;
            if(px <  || py <  || px >= n || py >= n)continue;
            if(ar[px][py] == 'O')continue;
            if(t.step>k)return ;
            if(t.ip == ) {
                if(vis[px][py][])continue;
                if(t.d != - && t.d != i)continue;
                if(t.d != -) {
                    now.d = -;now.ip=;
                    now.x = px; now.y = py;
                    vis[px][py][]=;
                    now.step = t.step + ;
                    if(ar[px][py]=='X')return now.step;
                    if(ar[px][py]=='C'){
                        now.ip=;
                        vis[px][py][]=;
                    }
                    Q.push(now);
                } else {
                    now.d = i;now.ip=;
                    now.x = t.x; now.y = t.y;
                    now.step = t.step + ;
                    Q.push(now);
                }
            }else{
                if(vis[px][py][])continue;
                now.d = i;now.ip=;
                now.x = px; now.y = py;
                now.step = t.step + ;
                if(ar[px][py]=='X')return now.step;
                vis[px][py][]=;
                Q.push(now);
            }
        }
    }
    return ;
}
int main()
{
    int t;
    scanf("%d", &t);
    while(t--) {
        int a, b;
        scanf("%d%d", &n, &k);
        for(int i = ; i < n; ++i) {
            scanf("%s", &ar[i]);
            for(int j = ; j < n; ++j) {
                if(ar[i][j] == 'S')a = i, b = j;
            }
        }
        int ans = bfs(a, b);
        if(ans!=&&ans<=k) {
            printf("YES\n%d\n", ans);
        } else {
            printf("NO\n");
        }
    }
    return ;
}
/*
3
2 3
.X
S.
2 3
.X
SC
2 4
.X
S.
*/

题目：

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