HDU 2102 A计划

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题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=2102

题解：

BFS+剪枝

1.题意不是很清楚，不太清楚S是否一定是（0,0,0），所以这里做了一次查找；

2.对于传送门的问题，如果两个传送门相对，那么骑士一定会被传送门华丽丽地玩死了；

3.剪枝，这里的剪枝由于两层之间传送不消耗时间，所以我们只需要求：T(当前位置)+DIS(公主位置-当前位置)<=T才能继续进行，否则就要被剪掉

代码：

#include <iostream>#include <cstdio>#include <cstdlib>#include <cstring>#include <cmath>#include <algorithm>#include <vector>#include <queue>#include <stack>#include <set>#include <map>using namespace std;#define Lowbit(x) ((x)&(-(x)))#define ll long long#define mp make_pair#define ff first#define ss second#define pb push_back#define mod 10000007//#define LOCAL#define MAXN 100010#define INF 1e9#define Max 100010int ty[]={0,1,0,-1};int tz[]={1,0,-1,0};char str[2][15][15];bool visit[2][15][15];int N,M,T;typedef struct node{    int x,y,z;    int cost;}NODE;bool check(int &x,int &y,int &z){    if(y<0||y>=N||z<0||z>=M||str[x][y][z]=='*'||visit[x][y][z])        return false;    visit[x][y][z] = true;    if(str[x][y][z]=='#')        if(str[x^1][y][z]=='*'||str[x^1][y][z]=='#')            return false;        else            x^=1;   //传送门进行层传递    visit[x][y][z] = true;    return true;}int main(){    int C;    scanf("%d",&C);    while(C--){        scanf("%d%d%d", &N, &M, &T);        int i,j,k;        for(i=0; i<2; ++i){            for(j=0; j<N; ++j)                scanf("%s", str[i][j]);        }        NODE now;        NODE target;        //查找'S'\'P'点的位置        for(i=0; i<2; ++i){            for(j=0; j<N; ++j){                for(k=0; k<M; ++k){                    if(str[i][j][k]=='S'){                        now.x = i;                        now.y = j;                        now.z = k;                    }                    if(str[i][j][k]=='P'){                        target.x = i;                        target.y = j;                        target.z = k;                    }                }            }        }        //BFS        memset(visit, false, sizeof(visit));        now.cost = 0;        queue<NODE> que;        que.push(now);        visit[now.x][now.y][now.z] = true;        bool flag = false;        while(que.size()){            now = que.front();            que.pop();            if(now.cost>T)  break;            if(now.x==target.x&&now.y==target.y&&now.z==target.z){                flag = true;                break;            }            NODE next;            for(i=0; i<4; ++i){                next.x = now.x;                next.y = now.y+ty[i];                next.z = now.z+tz[i];                next.cost = now.cost+1;                if(check(next.x,next.y,next.z)){                    //剪枝                    if(next.cost+                       abs(target.y-next.y)+abs(target.z-next.z)>T)                        continue;                    que.push(next);                }            }        }        printf("%s\n", flag?"YES":"NO");    }    return 0;}

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