ZOJ 3652 Maze 模拟,bfs,读题 难度:2

http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemId=4842

要注意题目中两点:

1.在踏入妖怪控制的区域那一刹那,先减行动力,然后才能杀妖怪

2.在妖怪控制区域行动力也会恢复

3.妖怪也许不在自己的控制区域

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue> using namespace std;
const int maxn=100;
const int dx[4] = {0,0,-1,1};
const int dy[4] = {1,-1,0,0};
int n,m,l,k,sx,sy,tx,ty;
int maz[maxn][maxn];
int mon[6][2]; int vis[maxn][maxn][maxn];
int ind[maxn][maxn];
struct P{
int x,y,sta,r;
P(){x = y = sta = r = 0;}
P(int _x,int _y,int _sta,int _r){
x = _x;
y = _y;
sta = _sta;
r = _r;
}
bool operator <(P p2)const {
if(vis[x][y][sta] != vis[p2.x][p2.y][p2.sta])
return vis[x][y][sta] > vis[p2.x][p2.y][p2.sta];
return r < p2.r;
}
};
int ok(int x,int y,int sta){
if(x < 1 || y < 1 || x > n || y > m)return -1;
int ki = maz[x][y];
if(ki == -1)return -1;
if(ki > 0){
if(sta & (1 << (ki-1)))return 1;
return 0;
}
return 1;
}
priority_queue <P> que;
int bfs(){
memset(vis ,-1, sizeof vis);
vis[sx][sy][0] = 0;
que.push(P(sx,sy,0,0));
while(!que.empty()){
P tp=que.top();que.pop();
// printf("pop x: %d y: %d sta: %d step %d turn %d\n",tp.x,tp.y,tp.sta,tp.r,vis[tp.x][tp.y][tp.sta]);
if(tx == tp.x && ty == tp.y)return vis[tx][ty][tp.sta];
for(int i = 0;i < 4;i++){
int tmpx = tp.x + dx[i];
int tmpy = tp.y + dy[i];
int sta = tp.sta;
if(ind[tmpx][tmpy] != 0)sta |= (1 << (ind[tmpx][tmpy] - 1));
if(ok(tmpx,tmpy,tp.sta) >= 0 && vis[tmpx][tmpy][sta] == -1){
if(tp.r == 0){
vis[tmpx][tmpy][sta] = vis[tp.x][tp.y][tp.sta] + 1;
// printf("push x: %d y: %d sta: %d step %d turn %d\n",
// tmpx,tmpy,sta,(ok(tmpx,tmpy,sta)==0?0:l-1),vis[tp.x][tp.y][tp.sta]+1);
que.push(P(tmpx,tmpy,sta,(ok(tmpx,tmpy,tp.sta) == 0?0:l-1)));
}
else {
vis[tmpx][tmpy][sta] = vis[tp.x][tp.y][tp.sta];
//printf("push x: %d y: %d sta: %d step %d turn %d\n",
// tmpx,tmpy,sta,(ok(tmpx,tmpy,sta)==0?0:tp.r-1),vis[tp.x][tp.y][tp.sta]);
que.push(P(tmpx,tmpy,sta,(ok(tmpx,tmpy,tp.sta) == 0?0:tp.r-1)));
}
}
}
}
return -1;
} int main(){
while(scanf("%d%d%d",&n,&m,&l) == 3){
while(!que.empty())que.pop();
memset(ind,0,sizeof ind);
for(int i = 1;i <= n;i++){
for(int j = 1;j <= m;j++){
scanf("%d",maz[i]+j);
}
}
scanf("%d",&k);
for(int i = 1;i <= k;i++){
scanf("%d%d",mon[i],mon[i] + 1);
ind[mon[i][0]][mon[i][1]]=i;
}
scanf("%d%d%d%d",&sx,&sy,&tx,&ty);
int ans = bfs();
if(ans < 0){
puts("We need God's help!");
}
else {
printf("%d\n",ans);
}
}
return 0;
}
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