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    POJ 1753

    BFS位运算

    #include <cstdio>
    #include <cstring>
    #include <iostream>
    #include <queue>
    using namespace std;
    
    int map[6][6];
    int change[16] = { 51200, 58368, 29184, 12544, 35968, 20032, 10016, 4880, 2248,
            1252, 626, 305, 140, 78, 39, 19 };
    int BFS(int state) {
        queue<pair<int, int> > Q;
        Q.push(make_pair(state, 0));
        int tmp;
        pair<int, int> cur;
        int vis[65536] = { 0 };
        while (!Q.empty()) {
            cur = Q.front();
            Q.pop();
            for (int i = 0; i < 16; i++) {
                tmp = cur.first ^ change[i];
                if (tmp == 0 || tmp == 65535)
                    return cur.second + 1;
                if (!vis[tmp])
                    Q.push(make_pair(tmp, cur.second + 1)), vis[tmp] = 1;
            }
        }
        return -1;
    }
    int main() {
    //    freopen("data.txt", "r", stdin);
        char tmp;
        while (~scanf("%c", &tmp)) {
            int state = 0;
            memset(map, 0, sizeof(map));
            map[1][1] = (tmp == 'b') ? 1 : 0;
            if (map[1][1])
                state += 1;
            for (int i = 1; i < 4; i++) {
                scanf("%c", &tmp);
                map[1][i] = (tmp == 'b') ? 1 : 0;
                if (map[1][i])
                    state += 1 << i;
            }
            for (int i = 2; i <= 4; i++) {
                getchar();
                for (int j = 1; j <= 4; j++) {
                    scanf("%c", &tmp);
                    map[i][j] = (tmp == 'b') ? 1 : 0;
                    if (map[i][j])
                        state += 1 << ((i - 1) * 4 + j - 1);
                }
            }
            getchar();
            if (state == 0 || state == 65535) {
                puts("0");
                continue;
            }
            int ans = BFS(state);
            ans == -1 ? puts("Impossible") : printf("%d
    ", ans);
        }
        return 0;
    }

    POJ 2965

    要求输出操作方式,DFS迭代加深。

    #include <iostream>
    #include <cstdio>
    using namespace std;
    
    int chess;
    int step;
    bool flag = 0;
    int ans[16];
    
    int flip[16] = { 0x111f, 0x222f, 0x444f, 0x888f, 0x11f1, 0x22f2, 0x44f4, 0x88f8,
            0x1f11, 0x2f22, 0x4f44, 0x8f88, 0xf111, 0xf222, 0xf444, 0xf888 };
    void dfs(int bit, int deep) {
        if (deep == step) {
            flag = (chess == 0) ? 1 : 0;
            return;
        }
        if (flag || bit > 15)
            return;
        ans[deep] = bit;
    
        chess ^= flip[bit];
        dfs(bit + 1, deep + 1);
        chess ^= flip[bit];
        dfs(bit + 1, deep);
    }
    
    int main() {
    //    freopen("data.txt", "r", stdin);
        char tmp;
        chess = 0;
        for (int i = 0; i < 4; i++) {
            for (int j = 0; j < 4; j++) {
                scanf("%c", &tmp);
                if (tmp == '+')
                    chess ^= (1 << (i * 4 + j));
            }
            if (i < 3)
                getchar();
        }
        for (step = 0;; step++) {
            dfs(0, 0);
            if (flag)
                break;
        }
        printf("%d
    ", step);
        for (int i = 0; i < step; i++)
            printf("%d %d
    ", ans[i] / 4 + 1, ans[i] % 4 + 1);
        return 0;
    }
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  • 原文地址:https://www.cnblogs.com/updateofsimon/p/3608757.html
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