leetcode-go/poj/4001.xiangqi/main.cc

#include <iostream>
#include <cstdio>
#include <cstring>

#define X 10
#define Y 9

using std::cin;

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

int hx[8] = {2, 2, 1, -1, -2, -2, 1, -1};
int hy[8] = {1, -1, 2, 2, 1, -1, -2, -2};

char board[X + 1][Y + 1];

bool is_out(int x, int y) {
    return x < 1 || X < x || y < 1 || Y < y;
}

bool solve(int x, int y) {
    // Out of black palace
    if (x < 1 || 3 < x || y < 4 || 6 < y) return true;
    // Check cannon and chariot
    for (int i = 0; i < 4; i++) {
        int nx = x + dx[i];
        int ny = y + dy[i];
        char c = 0;
        int gap = 0;
        while (gap < 2 && !is_out(nx, ny)) {
            c = board[nx][ny];
            nx += dx[i];
            ny += dy[i];
            if (c == 0) continue;
            switch (c) {
                case 'G': case 'R':
                    if (gap == 0) return true;
                    break;
                case 'C':
                    if (gap == 1) return true;
                    break;
            }
            gap++;
        }
    }
    for (int i = 0; i < 8; i++) {
        int nx = x + hx[i];
        int ny = y + hy[i];
        if (is_out(nx, ny)) continue;
        if (board[nx][ny] == 'H') {
            nx -= hx[i] / 2; // Red to black, not black to red!
            ny -= hy[i] / 2;
            if (board[nx][ny] == 0) return true;
        }
    }
    return false;
}

void print_board() {
    printf("  123456789\n");
    for (int x = 1; x <= X; x++) {
        printf("%2d", x);
        for (int y = 1; y <= Y; y++) {
            if (board[x][y] == 0) {
                printf(".");
            } else {
                printf("%c", board[x][y]);
            }
        }
        printf("\n");
    }
}

int main() {
    int N, gx, gy;
    for (;;) {
        cin >> N >> gx >> gy;
        if (N == 0 && gx == 0 && gy == 0) break;
        memset(board, 0, sizeof(board));
        char ch;
        int x, y;
        for (int n = 0; n < N; n++) {
            cin >> ch >> x >> y;
            board[x][y] = ch;
        }
        bool checkmate = true;
        for (int nx = gx + 1, ny = gy; !is_out(nx, ny); nx++) {
            char c = board[nx][ny]; // For "flying general"
            if (c == 0) continue;
            if (c == 'G') checkmate = false;
            break;
        }
        for (int i = 0; i < 4; i++) {
            int nx = gx + dx[i];
            int ny = gy + dy[i];
            checkmate &= solve(nx, ny);
        }
        printf(checkmate ? "YES\n" : "NO\n");
    }
}