【HDOJ】3451 Beat drop

BFS。当水滴破裂飞溅后，直到碰到水滴才会停止（观察case1）。同时，考虑当水滴飞溅到点（x，y）并且该点同一时间破裂的情况，该水滴算作吸收。

/* 3451 */
#include <iostream>
#include <queue>
#include <cstdio>
#include <cstring>
#include <cstdlib>
using namespace std;

#define MAXN 105

typedef struct node_t{
    int x,y,d,t;
    node_t() {}
    node_t(int xx, int yy, int dd, int tt) {
        x = xx; y = yy; d = dd; t = tt;
    }
} node_t;

node_t beg;
int bx, by;
int n, m, l;
int map[MAXN][MAXN];
int t[MAXN][MAXN];
int dir[4][2] = {
    -1,0,1,0,0,-1,0,1
};

inline bool check(int x, int y) {
    return x<0 || x>=n || y<0 || y>=m;
}

bool isValid() {
    int i, j;
    
    for (i=0; i<n; ++i)
        for (j=0; j<m; ++j)
            if (map[i][j])
                return false;
    return true;
}

void bfs() {
    int x, y, d;
    int i, j, k;
    node_t nd;
    queue<node_t> Q;
    
    memset(t, 0, sizeof(t));
    if (map[bx][by] == l) {
        map[bx][by] = 0;
        t[bx][by] = 1;
        nd.t = 2;
        for (i=0; i<4; ++i) {
            nd.x = bx + dir[i][0];
            nd.y = by + dir[i][1];
            if (check(nd.x, nd.y))
                continue;
            nd.d = i;
            Q.push(nd);
        }
    } else {
        ++map[bx][by];
        return ;
    }
    
    while (!Q.empty()) {
        nd = Q.front();
        Q.pop();
        if (map[nd.x][nd.y] == l) {
            // break
            map[nd.x][nd.y] = 0;
            t[nd.x][nd.y] = nd.t;
            for (i=0; i<4; ++i) {
                x = nd.x + dir[i][0];
                y = nd.y + dir[i][1];
                if (check(x, y))
                    continue;
                Q.push(node_t(x, y, i, nd.t+1));
            }
        } else if (map[nd.x][nd.y]) {
            // absorb
            ++map[nd.x][nd.y];
        } else if (t[nd.x][nd.y] != nd.t) {
            // no drop, continue fly
            x = nd.x + dir[nd.d][0];
            y = nd.y + dir[nd.d][1];
            if (check(x, y))
                continue;
            Q.push(node_t(x, y, nd.d, nd.t+1));
        }
    }
}

int main() {
    int t;
    int i, j, k;
    bool flag;
    
    #ifndef ONLINE_JUDGE
        freopen("data.in", "r", stdin);
        freopen("data.out", "w", stdout);
    #endif
    
    scanf("%d", &t);
    while (t--) {
        scanf("%d %d %d", &n, &m, &l);
        flag = false;
        for (i=0; i<n; ++i) {
            for (j=0; j<m; ++j) {
                scanf("%d", &map[i][j]);
            }
        }
        flag = isValid();
        scanf("%d", &k);
        while (k--) {
            scanf("%d %d", &bx, &by);
            --bx; --by;
            if (flag == false) {
                bfs();
                flag = isValid();
            }
        }
        if (flag) {
            puts("YES");
        } else {
            puts("NO");
            for (i=0; i<n; ++i) {
                for (j=0; j<m; ++j)
                    printf("%d ", map[i][j]);
                printf("
");
            }
        }
    }
    
    return 0;
}