BFS&DFS遍历

Posted 2022-11-20 Rgylin

深度和广度优先遍历

–``比如迷宫题目

https://www.acwing.com/problem/content/description/1115/

DFS代码为

#include <iostream>
#include <queue>

using namespace std;
const int N = 25;

struct node

    int x;
    int y;
;

int n,m;
int result1=0;
char g[N][N];
void dfs(int x,int y)
    int dx[4] = -1, 0, 1, 0, dy[4] = 0, 1, 0, -1;

    g[x][y]='#';
    for(int i=0;i<4;i++)
        int a= x+dx[i],b=y+dy[i];
        if(a>=0 && a<n && b>=0 && b<m && g[a][b]=='.')
            result1++;
      
            dfs(a,b);
        
    

int main()
    while(cin>>m>>n,n||m)
        result1=0;
        int x,y;
        for(int i=0; i<n;i++)cin>>g[i];
        for(int i=0; i<n; i++ )
            for(int j=0;j<m;j++)
                if(g[i][j]=='@')
                    x=i;
                    y=j;
                
            
        dfs(x,y);
        cout<<result1+1<<endl;
    
 

BFS代码为

#include <iostream>
#include <queue>

using namespace std;
const int N = 25;
struct node

    int x;
    int y;
;

int n,m;
char g[N][N];
int bfs(int x,int y)
    int dx[4] = -1, 0, 1, 0, dy[4] = 0, 1, 0, -1;
    int res=0;
    node N1,N2;
    N1.x=x;
    N1.y=y;
    g[x][y]='#';
    queue<node> q;
    q.push(N1);
    
    while (q.size())
        auto t = q.front();
        res++;
        q.pop();
        for(int i=0;i<4;i++)
            int Nx = t.x+dx[i];
            int Ny = t.y+dy[i];
            if(Nx >= 0 && Nx < n && Ny<m && Ny >= 0 && g[Nx][Ny]=='.')
            N2.x= Nx;
            N2.y= Ny;
            g[Nx][Ny]='#';
            q.push(N2);
            
        
    
    return res;

int main()
    while(cin>>m>>n,n||m)
        int x,y;
        for(int i=0; i<n;i++)cin>>g[i];
        for(int i=0; i<n; i++ )
            for(int j=0;j<m;j++)
                if(g[i][j]=='@')
                    x=i;
                    y=j;
                
            
        cout<<bfs(x,y)<<endl;