RE求调qwq

Lemon_zqp @ 2024-01-14 12:09:22

#include<bits/stdc++.h>
using namespace std;

bool mp[105][105];
int n, m;
int dx[5] = {-1, 1, 0, 0};
int dy[5] = {0, 0, -1, 1};

bool dfs(int x, int y){
    if(x == n && y == m){
        return true;
    }
    for(int i = 0; i < 4; i++){
        int nx = x + dx[i];
        int ny = y + dy[i];
        if(nx >= 1 && nx <= n && ny >= 1 && ny <= m && mp[nx][ny]){
            mp[nx][ny] = false;
            cout << nx << " " << ny << endl;
            dfs(nx, ny);
            mp[nx][ny] = true;
        }
    }
}

int main()
{
    cin >> n >> m;
    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= m; j++){
            char a;
            cin >> a;
            if(a == '.'){
                mp[i][j] = true;
            }
            else{
                mp[i][j] = false;
            }
        }
    }
    if(dfs(1, 1)){
        cout << "Yes";
    }
    else{
        cout << "No";
    }
    return 0;
}

by _int123_ @ 2024-01-14 12:43:41

@Lemon_zqp dfs里没有return false的操作，而且你代码显然tle

by _int123_ @ 2024-01-14 12:52:30

@Lemon_zqp 你可以试试bfs

AC 代码：

#include<bits/stdc++.h>
#define int long long
using namespace std;
int a[100][105],v[105][105];
int n,m;
struct node
{
    int x,y;
};
queue <node> q;
int dx[4]={1,-1,0,0};
int dy[4]={0,0,1,-1};
bool bfs(int x,int y)
{
    v[x][y]=1;
    q.push({x,y});
    while(!q.empty())
    {
        node w=q.front();
        q.pop();
        if(w.x==n&&w.y==m) return true;
        for(int i=0;i<4;i++)
        {
            int xx=w.x+dx[i];
            int yy=w.y+dy[i];
            if(xx>0&&yy>0&&xx<=n&&yy<=m&&v[xx][yy]==0&&a[xx][yy]==1)
            {
                q.push({xx,yy});
                v[xx][yy]=1;
            }
        }
    }
    return false;
}
signed main()
{
    ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
    cin>>n>>m;
    for(int i=1;i<=n;i++)
        for(int j=1;j<=m;j++)
        {
            char c;
            cin>>c;
            if(c=='.') a[i][j]=1;
        }
    if(bfs(1,1)==true) cout<<"Yes";
    else cout<<"No";
    return 0;
}

by Lemon_zqp @ 2024-01-15 13:00:06

@int123

我按照你的代码改了一下bfs，但……好像样例没过……

#include<bits/stdc++.h>
using namespace std;

bool mp[105][105];
int n, m;
int dx[5] = {-1, 1, 0, 0};
int dy[5] = {0, 0, -1, 1};

struct node{
    int x, y;
};

queue<node> q;

void bfs(int x, int y){
    mp[x][y] = false;
    q.push({x, y});
    while(!q.empty()){
        node w = q.front();
        q.pop();
        if(w.x == n && w.y == m){
            cout << "Yes";
            exit(0);
        }
        for(int i = 0; i < 4; i++){
            int nx = x + dx[i];
            int ny = y + dy[i];
            if(nx >= 1 && nx <= n && ny >= 1 && ny <= m && mp[nx][ny]){
                q.push({nx, ny});
                mp[nx][ny] = false;
            }
        }
    }

}

int main()
{
    cin >> n >> m;
    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= m; j++){
            char a;
            cin >> a;
            if(a == '.'){
                mp[i][j] = true;
            }
            else{
                mp[i][j] = false;
            }
        }
    }
    bfs(1, 1);
    cout << "No";
    return 0;
}