poj1024 bfs

这题写的很苦手啊，详解见poj discuss.

#include <iostream>
#include <string>
#include <queue>
using namespace std;
struct point{
       int x,y;
};
int g[101][101][5],cas,n,m,k,x1[1010],x2[1010],y1[1010],y2[1010];
int a[101][101],b[101][101],x,y;
bool ans,v[101][101];
string s;
void bfs1(int x,int y) {
     int c,d,cc,dd,key;
     point tmp;
     queue<point> q;
     while (!q.empty()) q.pop();
     a[x][y] = 0;
     tmp.x = x;
     tmp.y = y;
     q.push(tmp);
     while (!q.empty()) {
           cc = q.front().x;
           dd = q.front().y;
           key = a[cc][dd];
           q.pop();
           for (int k=0;k<4;k++) {
               c = cc;
               d = dd;
               if (g[c][d][k]) {
                  if (k==0) c++;
                  if (k==1) d++;
                  if (k==2) c--;
                  if (k==3) d--;
                  if (a[c][d]==-1) {
                                  a[c][d] = key+1;
                                  tmp.x = c;
                                  tmp.y = d;
                                  q.push(tmp);
                  }
               }
           }
     }
}
void bfs2(int x,int y) {
     int c,d,cc,dd,key;
     point tmp;
     queue<point> q;
     while (!q.empty()) q.pop();
     b[x][y] = 0;
     tmp.x = x;
     tmp.y = y;
     q.push(tmp);
     while (!q.empty()) {
           cc = q.front().x;
           dd = q.front().y;
           key = b[cc][dd];
           q.pop();
           for (int k=0;k<4;k++) {
               c = cc;
               d = dd;
               if (g[c][d][k]) {
                  if (k==0) c++;
                  if (k==1) d++;
                  if (k==2) c--;
                  if (k==3) d--;
                  if (b[c][d]==-1) {
                                  b[c][d] = key+1;
                                  tmp.x = c;
                                  tmp.y = d;
                                  q.push(tmp);
                  }
               }
           }
     }
}                                          
int main() {
    scanf("%d",&cas);
    while (cas--) {
          scanf("%d%d",&n,&m);
          cin >> s;
          memset(g,1,sizeof(g));
          for (int i=0;i<n;i++)
              g[i][0][3] = g[i][m-1][1] = 0;
          for (int i=0;i<m;i++)
              g[0][i][2] = g[n-1][i][0] = 0;
          scanf("%d",&k);
          for (int i=1;i<=k;i++) {
              scanf("%d%d%d%d",&x1[i],&y1[i],&x2[i],&y2[i]);
              if (x1[i]==x2[i]) {
                 if (y1[i]<y2[i]) {
                                  g[x1[i]][y1[i]][1] = 0;
                                  g[x2[i]][y2[i]][3] = 0;
                 }
                 else {
                                  g[x1[i]][y1[i]][3] = 0;
                                  g[x2[i]][y2[i]][1] = 0;
                 }
              }
              else {
                 if (x1[i]<x2[i]) {
                                  g[x1[i]][y1[i]][0] = 0;
                                  g[x2[i]][y2[i]][2] = 0;
                 }
                 else {
                                  g[x1[i]][y1[i]][2] = 0;
                                  g[x2[i]][y2[i]][0] = 0;
                 }
              }
          }
          memset(v,0,sizeof(v));
          x = 0;
          y = 0;
          v[x][y] = 1;
          for (int i=0;i<s.length();i++) {
              if (s[i]=='R') x++;
              if (s[i]=='L') x--;
              if (s[i]=='U') y++;
              if (s[i]=='D') y--;
              v[x][y] = 1;
          }
          memset(a,-1,sizeof(a));
          memset(b,-1,sizeof(b));
          bfs1(0,0);
          bfs2(x,y);
          ans = true;
          for (int i=0;i<n;i++)
              for (int j=0;j<m;j++)
                  if (v[i][j]==0 && a[i][j]+b[i][j]==s.length())
                     ans = false;
          if (ans) {
                   for (int i=1;i<=k;i++) 
                       if (a[x1[i]][y1[i]]+b[x2[i]][y2[i]]>s.length() &&
                          a[x2[i]][y2[i]]+b[x1[i]][y1[i]]>s.length()) {
                          ans = false;
                          break;
                       }
          }
          for (int j=m-1;j>=0;j--)    //全围起来！！ 
              for (int i=0;i<n;i++)
                  if (a[i][j]==-1) {
                                   ans = false;
                                   break;
                  }
          
          if (ans) printf("CORRECT\n");
          else printf("INCORRECT\n");
    }
    return 0;
}