GF-2023秋季集训=DFS-地图路径

O1458迷宫路径

#include <iostream>
using namespace std;
int n,m,d[]{0,1,0,-1,0},ans=0,step;
     //dy[]{1,0,-1,0};
char g[55][55];
struct node{
	int x,y;
}a[10005];

void dfs(int x,int y){
	if(x<1 || y<1 || x>n || y>m )return;
	if(g[x][y]=='#')return;
	if(x==n && y==m){
		ans++;
		cout<<ans<<":";
		for(int i=1;i<=step;i++){
			cout<<a[i].x<<","<<a[i].y<<"->";
		}
		cout<<x<<","<<y<<endl;
		return;
	}
	for(int i=0;i<4;i++){
		int nx=x+d[i];
		int ny=y+d[i+1];
		step++;
		g[x][y]='#'; //.->#
		a[step].x=x; //a[step]=(node){x,y};
		a[step].y=y; //0->y
		dfs(nx,ny);
		a[step].y=0; //y->0  回溯 
		a[step].x=0; //x->0
		g[x][y]='.';
		step--;
	}	
}
int main(){
	cin>>n>>m;
	for(int i=1;i<=n;i++)
		for(int j=1;j<=m;j++)cin>>g[i][j];
	dfs(1,1);
	if(ans==0)cout<<"no";
	return 0;
}

O1452

#include <bits/stdc++.h>
using namespace std;
const int INF=0x3f3f3f3f;
int n,m,sx,sy,tx,ty,step,ans=INF,dx[]{0,0,1,-1},dy[]{1,-1,0,0};
char g[55][55];
int f[55][55];
void dfs(int x,int y){
	/*
	if(x==tx&&y==ty){
		ans=min(ans,step);return;
	}*/
	if(step>f[x][y])return;
	f[x][y]=step;
	for(int i=0;i<4;i++){
		int nx=x+dx[i],ny=y+dy[i];
		char t=g[nx][ny];
		if(t!='#'){
			step++;			
			if(t=='x')step++;
			g[nx][ny]='#';
			dfs(nx,ny);
			g[nx][ny]=t;
			if(t=='x')step--;
			step--;
		}
	}
}
int main() {
	memset(g,'#',sizeof(g));
	memset(f,0x3f,sizeof(f));
	cin>>n>>m;
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			cin>>g[i][j];
			if(g[i][j]=='r')sx=i,sy=j;
			if(g[i][j]=='a')tx=i,ty=j;
		}
	}
	g[sx][sy]='#';g[tx][ty]='@';step=0;
	dfs(sx,sy);
	ans=f[tx][ty];
	if(ans==INF)cout<<"Impossible";
	else cout<<ans;
	return 0;
}