走迷宫BFS算法

#include<iostream>
#include<queue>
#include<stack>
#include<iomanip>
using namespace std;

int map[40][40];
int done[40][40];

int dx[4] = { 0,0,1,-1 };
int dy[4] = { 1,-1,0,0 };

struct Node
{
    int x, y, step;
};

int main() {
    int n,ex,ey;
    cin >> n>>ex>>ey;

    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= n; j++)
            done[i][j] = -1;

    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= n; j++)
            cin >> map[i][j];
    
    queue<Node> q;
    q.push(Node({1,1,0}));
    done[1][1] = 0;
    while (!q.empty())
    {
        //cout << q.front().x << ":" << q.front().y << ":" << q.front().step << endl;
        for (int i = 0; i < 4; i++)
        {
            int tx = q.front().x + dx[i];
            int ty = q.front().y + dy[i];
            
            if (tx>=1&&ty>=1&&tx<=n&&ty<=n&&done[tx][ty]==-1&&!map[tx][ty])
            {
                q.push(Node({ tx,ty,q.front().step+1 }));
                done[tx][ty] = q.front().step + 1;
            }
        }
        q.pop();
    }

    cout << endl;

    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n; j++) {
            if (done[i][j] != -1) cout << left <<setw(2) << done[i][j];
            else cout << left << setw(2) << "□";
        }
        cout << endl;
    }
    
    for (int i = 0; i <= n+1; i++)
        for (int j = 0; j <= n + 1; j++)
            if (i == 0 || i == n + 1 || j == 0 || j == n + 1) done[i][j] = -10;
    int ttx = ex, tty = ey;
    int step = done[tty][ttx];
    stack<char> result;
    while (step)
    {
        step--;
        if (done[tty][ttx-1] == step) {
            //cout << "L"; 
            ttx--; result.push('R');
        }else
        if (done[tty][ttx+1] == step) {
            //cout << "R"; 
            ttx++; result.push('L');
        }else
        if (done[tty-1][ttx] == step) {
            //cout << "U"; 
            tty--; result.push('D');
        }else
        if (done[tty+1][ttx] == step) {
            //cout << "D"; 
            tty++; result.push('U');
        }
    }
    while (!result.empty())
    {
        cout << result.top();
        result.pop();
    }

    return 0;
}

运用技术：BFS算法/栈结构和队列结构