可以把这个题与马走日那一题进行一个对比：

AcWing 1116. 马走日

#include <iostream>
#include <queue>
using namespace std;
typedef pair<int, int> PII;
int C, R;
char g[155][155];
int d[155][155];
int x, y, H_x, H_y;
int dx[] = {-2, -1, 1, 2, 2, 1, -1, -2};
int dy[] = {1, 2, 2, 1, -1, -2, -2, -1};
void bfs(int x, int y) {
    queue<PII> q;
    q.push({x, y}); d[x][y] = 0;
    while (q.size()) {
        auto t = q.front(); q.pop();
        for (int i = 0; i < 8; i++) {
            int a = dx[i] + t.first, b = dy[i] + t.second;
            if (d[a][b] || g[a][b] == '*') continue;
            if (a < 0 || a >= C || b < 0 || b >= R) continue;
            d[a][b] = 1 + d[t.first][t.second];
            q.push({a, b});
        }
    }
}
int main() {
    cin >> R >> C;
    for (int i = 0; i < C; i++)
        scanf("%s", g[i]);
    for (int i = 0; i < C; i++)
        for (int j = 0; j < R; j++) {
            if (g[i][j] == 'K') 
                x = i, y = j;
            if (g[i][j] == 'H')
                H_x = i, H_y = j;
        }
    bfs(x, y);
    cout << d[H_x][H_y] << endl;
    return 0;
}

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