DFS,BFS

D-ACM中的AC题_牛客小白月赛100

#include "bits/stdc++.h"
#define int long long
using namespace std;
const int N=3e3+10;
int n,m,sx,sy;
char a[N][N]; 
int dist[N][N];
bool st[N][N];
int dx[4]={1,-1,0,0};
int dy[4]={0,0,1,-1};
struct nodep{int px,py,pcnt;
};
struct nodeq{int qx1,qy1,qx2,qy2,qcnt;
};
signed main()
{ios::sync_with_stdio(0);cin.tie(0),cout.tie(0);
cin>>n>>m>>sx>>sy;
memset(dist,-1,sizeof(dist));
queue<nodep>p;
for(int i=1;i<=n;i++)for(int j=1;j<=m;j++){cin>>a[i][j];if(a[i][j]=='@')p.push({i,j,0});} while(!p.empty()){nodep w=p.front();p.pop();int x=w.px;int y=w.py;int cnt=w.pcnt;if(dist[x][y]!=-1)//RRRRRcontinue;dist[x][y]=cnt;for(int i=0;i<4;i++){int tx=x+dx[i];int ty=y+dy[i];if(tx<1||tx>n||ty<1||ty>m||dist[tx][ty]!=-1) continue;if(a[tx][ty]=='.')p.push({tx,ty,cnt+1});	}}queue<nodeq>q;q.push({sx,sy,sx,sy,0});int ans=100000000000000;while(q.empty()==0){nodeq ww=q.front();q.pop();int x1=ww.qx1;int y1=ww.qy1;int x2=ww.qx2;int y2=ww.qy2;int cnt=ww.qcnt;if(st[x1][y1]) continue;st[x1][y1]=true;for(int i=0;i<4;i++){int ix=x1+dx[i];int iy=y1+dy[i];int jx=x2-dx[i];int jy=y2-dy[i];if(ix<1||ix>n||iy<1||iy>m||st[ix][iy])continue;if(jx<1||jx>n||jy<1||jy>m)continue;if(a[ix][iy]=='@'&&a[jx][jy]!='#')ans=min(ans,cnt+1+dist[jx][jy]);if(a[ix][iy]=='.'&&a[jx][jy]=='.')q.push({ix,iy,jx,jy,cnt+1});}
}
if(ans==100000000000000) ans=-1;
cout<<ans<<'\n';
}