JZOJ P1830[9.30]送牛奶

传送门

临近NOIp，写一些简单题。

二分+BFS，注意的是要把数组开小点，有效减少memset的时间。

 //OJ 1830
 //by Cydiater
 //2016.9.22
 #include <iostream>
 #include <cstdio>
 #include <cstring>
 #include <string>
 #include <algorithm>
 #include <queue>
 #include <map>
 #include <ctime>
 #include <cmath>
 #include <cstdlib>
 #include <iomanip>
 using namespace std;
 #define ll long long
 #define up(i,j,n)        for(int i=j;i<=n;i++)
 #define down(i,j,n)        for(int i=j;i>=n;i--)
 ;
 const int oo=0x3f3f3f3f;
 ]={,,,,,-,-,-};
 ]={,-,,,-,,,-};
 inline int read(){
     ,f=;
     ;ch=getchar();}
     +ch-';ch=getchar();}
     return x*f;
 }
 ][],N,stx,sty,num[MAXN],top=,leftt,rightt,mid,head,tail,cnt=,remain=;
 pair<int,int>q[MAXN];
 ][],vis[][];
 namespace solution{
     inline bool yes(int num,int low,int high){return num>=low&&num<=high;}
     inline void push(int x,int y){q[++tail]=make_pair(x,y);}
     void init(){
         cnt=;
         memset(ok,,;
         up(i,,N){
             scanf("\n");
             up(j,,N){
                 char ch;scanf("%c",&ch);
                 ok[i][j]=ch==:;
                 cnt+=ok[i][j];
                 if(ch=='P'){
                     stx=i;sty=j;
                 }
             }
         }
         up(i,,N)up(j,,N)height[i][j]=read();
         up(i,,N)up(j,,N)num[++top]=height[i][j];
         sort(num+,num+N*N+);
     }
     bool nxt_check(int low,int high){
         head=;tail=;remain=cnt;
         memset(vis,,sizeof(vis));
         if(yes(height[stx][sty],low,high))push(stx,sty);
         for(;head<=tail;head++){
             pair<int,int> node=q[head];
             int x=node.first,y=node.second;
             ){
                 vis[x][y]=;
                 if(ok[x][y])remain--;
             }else continue;
             );
             up(i,,){
                 int tx=x+dx[i],ty=y+dy[i];
                 &&tx<=N&&ty>=&&ty<=N&&yes(height[tx][ty],low,high))push(tx,ty);
             }
         }
         ;
     }
     bool check(int delta){
         up(i,,N*N)]);
         ;
     }
     int slove(){
         leftt=;rightt=;
         <rightt){
             mid=(leftt+rightt)>>;
             if(check(mid))    rightt=mid;
             else            leftt=mid;
         }
         if(check(leftt))return leftt;
         else            return rightt;
     }
 }
 int main(){
     //freopen("input.in","r",stdin);
     using namespace solution;
     while(scanf("%d",&N)!=EOF){
         init();
         printf("%d\n",slove());
     }
     ;
 }