我不理解啊,哪里错了
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我不理解啊,哪里错了
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wusihao1931楼主2022/10/16 09:51
#include <queue>
#include <cstdio>
#include <cstring>
#include <iostream>

#define x first
#define y second

using namespace std;

typedef long long LL;
typedef pair<int, int> PII;

const int N = 35, M = N * N , E = M * N;

int n, m;
LL cnt[M];
bool vis[M];
LL dist[M];
int idx[N][N];
bool st[N][N];
int map[N][N];
PII start, last;
int h[M], e[E], ne[E], w[E], idxs;
int dx[8] = {2, 2, -2, -2, 1, -1, 1, -1};
int dy[8] = {-1, 1, -1, 1, 2, 2, -2, -2};

void add(int a, int b)
{
    e[idxs] = b;
    ne[idxs] = h[a];
    h[a] = idxs;
    idxs ++ ;
}

void dfs(int x, int y)
{
    if (st[x][y]) return ;

    st[x][y] = true;
    
    for (int i = 0; i < 8; i ++ )
    {
        int a = x + dx[i], b = y + dy[i];
        if (a < 1 || a > n || b < 1 || b > m) continue;
        if (st[a][b]) continue;
       
        if (map[a][b] == 1) dfs(a, b);
        else if (map[a][b] != 2)
        {
            st[a][b] = true;
            add(idx[x][y],  idx[a][b]);
        }
    }
}

void spfa(int S)
{
    queue<int> q;
    q.push(S);
    memset(dist, 0x3f, sizeof dist);
    dist[S] = 0;
    cnt[S] = 1;
    
    while (q.size())
    {
        int t = q.front();
        q.pop();
        
        vis[t] = false;
        
        for (int i = h[t]; i != -1; i = ne[i])
        {
            int j = e[i];
            if (dist[j] > dist[t] + 1)
            {
                cnt[j] = cnt[t];
                dist[j] = dist[t] + 1;
                if (!vis[j])
                {
                    q.push(j);
                    vis[j] = true;
                }
            }
            else if (dist[j] == dist[t] + 1) cnt[j] += cnt[t];
        }
    }
}

int main()
{
    cin >> n >> m;
    memset(h, -1, sizeof h);
    
    for (int i = 1, t = 0; i <= n; i ++ )
        for (int j = 1; j <= m; j ++ )
        {
            cin >> map[i][j];
            idx[i][j] = ++ t;
            if (map[i][j] == 3) start = {i, j};
            if (map[i][j] == 4) last = {i, j};
        }
    
    for (int i = 1; i <= n; i ++ )
        for (int j = 1; j <= m; j ++ )
            if (map[i][j] == 0 || map[i][j] == 3)
            {
                memset(st, false, sizeof st);
                dfs(i, j);
            }
    
    spfa(idx[start.x][start.y]);
    if (dist[idx[last.x][last.y]] == 0x3f3f3f3f) puts("-1");
    else
    {
        cout << dist[idx[last.x][last.y]] - 1<< endl;
        cout << cnt[idx[last.x][last.y]] << endl;
    }
    
    return 0;
}
2022/10/16 09:51
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