BFS DFS IDA* 走迷宫

题目

解法

BFS

//BFS
#include<bits/stdc++.h>
#define inf 0x3f3f3f3f
using namespace std;
bool mp[10][10];//0路,1墙 
bool vis[10][10];//0没走过,1走过
int dx[8]={-1,0,1,-1,1,-1,0,1};
int dy[8]={1,1,1,0,0,-1,-1,-1};
int m,n;//mp规模 
int ans=inf;
struct node{
	int x,y,step;//step表示距离起点的距离 
}now,next,start,end;
queue<node> q;
bool judge(int x,int y){
	if(x==0||y==0||x>m||y>n||vis[x][y]||mp[x][y])	return false;
	return true;
}
void bfs(void){
	q.push(start);
	while(!q.empty()){
		now=q.front();
		q.pop();
		if(now.x==end.x&&now.y==end.y){
			ans=min(ans,now.step);
			return;
		}
		for(int i=0;i<8;i++){
			if(judge(now.x+dx[i],now.y+dy[i])){
				next.x=now.x+dx[i],next.y=now.y+dy[i],next.step=now.step+1;
				q.push(next);
				vis[next.x][next.y]=true;
			}
		}
	}
}
int main(){
	cin>>m>>n;
	for(int i=1;i<=m;i++)
		for(int j=1;j<=n;j++)
			cin>>mp[i][j];
	start.x=1,start.y=1,start.step=0;end.x=m,end.y=n;
	vis[1][1]=true,bfs();
	ans==inf?puts("cbl can not find his npy"):printf("%d",ans);
	return 0;
} 

DFS

//DFS
#include<bits/stdc++.h>
#define inf 0x3f3f3f3f
using namespace std;
bool mp[10][10];//0路,1墙 
bool vis[10][10];//0没走过,1走过
int dx[8]={-1,0,1,-1,1,-1,0,1};
int dy[8]={1,1,1,0,0,-1,-1,-1};
int m,n;//mp规模 
int ans=inf;
bool judge(int x,int y){
	if(x==0||y==0||x>m||y>n||vis[x][y]||mp[x][y])	return false;
	return true;
}
void dfs(int x,int y,int step){
	if(x==m&&y==n){
		ans=min(ans,step);
		return;
	}
	if(step>=ans)	return;
	for(int i=0;i<8;i++){
		int nx=x+dx[i],ny=y+dy[i];
		if(judge(nx,ny)){
			vis[nx][ny]=true;
			dfs(nx,ny,step+1);
			vis[nx][ny]=false;
		}
	}	
}
int main(void){
	cin>>m>>n;
	for(int i=1;i<=m;i++)
		for(int j=1;j<=n;j++)
			cin>>mp[i][j];
	vis[1][1]=true;
	dfs(1,1,0);
	ans==inf?puts("cbl can not find his npy"):printf("%d",ans);
	return 0;
}

DFS剪枝版本

//IDA*
#include<bits/stdc++.h>
using namespace std;
bool mp[10][10];//0路,1墙 
bool vis[10][10];//0没走过,1走过
int dx[8]={-1,0,1,-1,1,-1,0,1};
int dy[8]={1,1,1,0,0,-1,-1,-1};
int m,n;//mp规模 
int ans=-1;
bool judge(int x,int y){
	if(x==0||y==0||x>m||y>n||vis[x][y]||mp[x][y])	return false;
	return true;
}
bool ida(int x,int y,int step,int maxstep){	
	if(step>maxstep)	return false;
	if(x==m&&y==n)		return true;
	for(int i=0;i<8;i++){
		int nx=x+dx[i],ny=y+dy[i];
		if(judge(nx,ny)){
			vis[nx][ny]=true;
			if(ida(nx,ny,step+1,maxstep))	return true;
			vis[nx][ny]=false;
		}
	}
	return false;	
}
int main(void){
	cin>>m>>n;
	for(int i=1;i<=m;i++)
		for(int j=1;j<=n;j++)
			cin>>mp[i][j];
	vis[1][1]=true;
	for(int i=1;i<=m*n;i++){
		if(ida(1,1,0,i)){
			ans=i;
			break;
		}
	}	
	ans==-1?puts("cbl can not find his npy"):printf("%d",ans);
	return 0;
}