CCF 201312-5I’m stuck!

来源：互联网发布：oracle数据库sqlplus 编辑：程序博客网时间：2024/05/16 14:05

//主要利用宽度优先算法。把S出发的能够到达的点都保存栈中。然后遍历所有栈中的点，调用bfs算法，看是否能到达终点。如果能计数

//sum++. 所有最后的点就是能够到达的点减去sum 再减去1（因为T在栈中时，不计数sum）

#include<iostream>
#include<stdio.h>
#include<stdlib.h>
#include <vector>
#include <queue>
#include <stack>
#include <cstring>
using namespace std;

typedef struct point{
   int x;
   int y;
}point;

vector<point> reach;
queue<point> q;   //BFS
stack<point> s; // 开始可以到达的点
int sum = 0;
int flag = false;//标志bfs运行的具体内容

#define N 51
int hang = 0,lie = 0;
int startx,starty,endx,endy;

char map[N][N];
int visit[N][N];

int gox [4] = {1,-1,0,0} ; //上下左右
int goy[4]={0,0,1,-1};

void shizhou(int x,int y){
       for(int i = 0;i<4;i++)
       {
           int tempx = x+gox[i];
           int tempy = y+goy[i];
           if(tempx<1||tempy<1 || tempx>hang || tempy>lie || map[tempx][tempy]=='#'){
               continue;
           }else{
               if(visit[tempx][tempy]==0&&flag== false){
                   point p1;
                   visit[tempx][tempy]=1;
                   p1.x = tempx;
                   p1.y = tempy;
                   q.push(p1);
                   s.push(p1);
               }else if(visit[tempx][tempy]==0&&flag== true){
                   point p1;
                   visit[tempx][tempy]=1;
                   p1.x = tempx;
                   p1.y = tempy;
                   q.push(p1);
                   if(tempx==endx&&tempy==endy){
                       sum++;
                   }
               }
           }
       }
}

void shangxia(int x, int y){

       for(int i = 0;i<=1;i++)
       {
           int tempx = x+gox[i];
           int tempy = y+goy[i];
           if(tempx<1||tempy< 1|| tempx>hang||tempy>lie||map[tempx][tempy]=='#'){
               continue;
           }else{
               if(visit[tempx][tempy]==0&&flag== false){
                   point p1;
                   visit[tempx][tempy]=1;
                   p1.x = tempx;
                   p1.y = tempy;
                   q.push(p1);
                   s.push(p1);
               }else if(visit[tempx][tempy]==0&&flag== true){
                   point p1;
                   visit[tempx][tempy]=1;
                   p1.x = tempx;
                   p1.y = tempy;
                   q.push(p1);
                   if(tempx==endx&&tempy==endy){
                       sum++;
                   }
               }
           }
       }
}

void zuoyou(int x, int y){

       for(int i = 2;i<=3;i++)
       {
           int tempx = x+gox[i];
           int tempy = y+goy[i];
           if(tempx<1||tempy<1||tempx>hang||tempy>lie||map[tempx][tempy]=='#'){
               continue;
           }else{
               if(visit[tempx][tempy]==0&&flag== false){
                   point p1;
                   visit[tempx][tempy]=1;
                   p1.x = tempx;
                   p1.y = tempy;
                   q.push(p1);
                   s.push(p1);
               }else if(visit[tempx][tempy]==0&&flag== true){
                   point p1;
                   visit[tempx][tempy]=1;
                   p1.x = tempx;
                   p1.y = tempy;
                   q.push(p1);
                   if(tempx==endx&&tempy==endy){
                       sum++;
                   }
               }
           }
       }
}

void xia(int x,int y){
   for(int i = 0;i<=0;i++)
       {
           int tempx = x+gox[i];
           int tempy = y+goy[i];
           if(tempx<1||tempy<1||tempx>hang||tempy>lie||map[tempx][tempy]=='#'){
               continue;
           }else{
               if(visit[tempx][tempy]==0&&flag== false){
                   point p1;
                   visit[tempx][tempy]=1;
                   p1.x = tempx;
                   p1.y = tempy;
                   q.push(p1);
                   s.push(p1);
               }else if(visit[tempx][tempy]==0&&flag== true){
                   point p1;
                   visit[tempx][tempy]=1;
                   p1.x = tempx;
                   p1.y = tempy;
                   q.push(p1);
                   if(tempx==endx&&tempy==endy){
                       sum++;
                   }
               }
           }
       }
}

void bfs() {
   while(!q.empty()){
       point p = q.front();
       q.pop();
       int x = p.x;
       int y = p.y;
       visit[x][y] = 1;

       switch(map[x][y]){
           case 'S': case '+' : case 'T' :{
               shizhou(x,y);
               break;
           }
           case '|':{
               shangxia(x,y);
               break;
           }
           case '-': {
               zuoyou(x,y);
               break;
           }
           case '.':{
               xia(x,y);
               break;
           }
       }
   }
}

void bfs(queue<point> q) {
   while(!q.empty()){
       point p = q.front();
       q.pop();
       int x = p.x;
       int y = p.y;
       visit[x][y] = 1;

       switch(map[x][y]){
           case 'S': case '+' : case 'T' :{
               shizhou(x,y);
               break;
           }
           case '|':{
               shangxia(x,y);
               break;
           }
           case '-': {
               zuoyou(x,y);
               break;
           }
           case '.':{
               xia(x,y);
               break;
           }
       }
   }
}
int main(){

   cin >>hang>>lie;

   for(int i = 1;i<=hang;i++)
   {
       for(int j = 1;j<=lie;j++)
       {
           cin >>map[i][j];

           if(map[i][j]=='S'){
               startx = i;
               starty = j;
           }else if(map[i][j]=='T'){
               endx = i;
               endy = j;
           }
       }
   }

//   cout << startx <<" "<<starty<<endl;
//   cout <<endx <<" " << endy<<endl;


   point p1;
   p1.x = startx;
   p1.y = starty;
   q.push(p1);

   flag = false;
   bfs();
   //可达
   //cout <<"可达："<<endl;
   flag = true; //开启另一个bfs


   bool firstReach = false;
   int num = s.size();
   if(s.empty()){
       cout <<"I'm stuck!";
   }else{
       while(!s.empty())
       {
           point p = s.top();
           s.pop();
           if(endx == p.x && endy == p.y){
               firstReach = true;
           }
           memset(visit,0,sizeof(visit)); //清零
           //清理q
           while(!q.empty()) {
               q.pop();
           }

           q.push(p);
           bfs();
       }
   }
   if(firstReach){
       cout << num-sum-1;   //sum 就是可以从S到达的点，还可以到达T的 (-1是因为T本身不算)
   }else{

       cout <<"I'm stuck!";
   }



   return 0;

}

0 0