HDU 4069 Squiggly Sudoku【Dancing Links精确覆盖】

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跟普通的数独有一点点不同，先预处理一下再用Dancing Links进行精确覆盖即可。
#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int maxn = 9*9*9*9*9*4 + 10;const int oo = 1 << 30;const int maxrow = 9*9*9 + 10;const int maxcol = 9*9*4 + 10;int mtx[maxrow][maxcol];int sub[10][10];int map[10][10];int ansMap[10][10];int totRow, totCol, head, idx;int L[maxn], R[maxn], U[maxn], D[maxn];int RH[maxn], CH[maxn], S[maxn];int t, ans;void initMtx(){    memset(mtx, 0, sizeof(mtx));    for (int i = 0; i < 9; ++i) {        for (int j = 0; j < 9; ++j) {            int t = i * 9 + j;            if (map[i][j] == 0) {                for (int k = 0; k < 9; ++k) {                    int row = t * 9 + k;                    mtx[row][t] = 1;                    mtx[row][i*9+k+81] = 1;                    mtx[row][j*9+k+162] = 1;                    mtx[row][sub[i][j]*9+k+243] = 1;                }            } else {                int k = map[i][j] - 1;                int row = t * 9 + k;                mtx[row][t] = 1;                mtx[row][i*9+k+81] = 1;                mtx[row][j*9+k+162] = 1;                mtx[row][sub[i][j]*9+k+243] = 1;            }        }    }}int newNode(int up, int down, int left, int right){    U[idx] = up;    D[idx] = down;    L[idx] = left;  R[idx] = right;    U[down] = D[up] = L[right] = R[left] = idx;    return idx++;}void build(){    idx = maxn - 1;    head = newNode(idx, idx, idx, idx);    idx = 0;    for (int j = 0; j < totCol; ++j) {        newNode(idx, idx, L[head], head);        CH[j] = j;  S[j] = 0;    }    for (int i = 0; i < totRow; ++i) {        int k = -1;        for (int j = 0; j < totCol; ++j) {            if (!mtx[i][j]) continue;            if (-1 == k) {                k = newNode(U[CH[j]], CH[j], idx, idx);                RH[k] = i;  CH[k] = j;  S[j]++;            } else {                k = newNode(U[CH[j]], CH[j], k, R[k]);                RH[k] = i;  CH[k] = j;  S[j]++;            }        }    }}inline void remove(int c){    L[R[c]] = L[c];    R[L[c]] = R[c];    for (int i = D[c]; i != c; i = D[i]) {        for (int j = R[i]; j != i; j = R[j]) {            U[D[j]] = U[j];  D[U[j]] = D[j];  S[CH[j]]--;        }    }}inline void resume(int c){    L[R[c]] = c;    R[L[c]] = c;    for (int i = U[c]; i != c; i = U[i]) {        for (int j = L[i]; j != i; j = L[j]) {            U[D[j]] = j;  D[U[j]] = j;  S[CH[j]]++;        }    }}int dance(){    if (R[head] == head) {        if (ans == 0) {            for (int i = 0; i < 9; ++i) {                for (int j = 0; j < 9; ++j) {                    ansMap[i][j] = map[i][j];                }            }         }        return ++ans;    }    int i, j, k, c, min = oo;    for (j = R[head]; j != head; j = R[j]) {        if (S[j] < min) {            min = S[j];  c = j;        }    }    remove(c);    for (i = D[c]; i != c; i = D[i]) {        k = RH[i];        map[k/9/9][(k/9)%9] = (k % 9) + 1;        for (j = R[i]; j != i; j = R[j]) {            remove(CH[j]);        }        if (dance() >= 2) {            return 2;        }        for (j = L[i]; j != i; j = L[j]) {            resume(CH[j]);        }        map[k/9/9][(k/9)%9] = 0;    }    resume(c);    return 0;}inline bool hasWall(int x, int y, int d){    int tmp = map[x][y] / 16;    return tmp & (1 << d);}void dfs(int x, int y, int id){    if (sub[x][y] != -1) {        return ;    }    sub[x][y] = id;    if (!hasWall(x, y, 0)) {        dfs(x - 1, y, id);    }    if (!hasWall(x, y, 1)) {        dfs(x, y + 1, id);     }    if (!hasWall(x, y, 2)) {        dfs(x + 1, y, id);    }    if (!hasWall(x, y, 3)) {        dfs(x, y - 1, id);    }}int main(){    totRow = 9*9*9, totCol = 9*9*4;    scanf("%d", &t);    for (int cas = 1; cas <= t; ++cas) {        for (int i = 0; i < 9; ++i) {            for (int j = 0; j < 9; ++j) {                scanf("%d", &map[i][j]);            }         }        memset(sub, -1, sizeof(sub));        int id = 0;        for (int i = 0; i < 9; ++i) {            for (int j = 0; j < 9; ++j) {                if (sub[i][j] == -1) {                    dfs(i, j, id);                    id++;                }            }        }        for (int i = 0; i < 9; ++i) {            for (int j = 0; j < 9; ++j) {                map[i][j] %= 16;            }        }        initMtx();        build();        ans = 0;        dance();                printf("Case %d:\n", cas);        if (ans == 0) {            printf("No solution\n");        } else if (ans > 1) {            printf("Multiple Solutions\n");        } else {            for (int i = 0; i < 9; ++i) {                for (int j = 0; j < 9; ++j) {                    printf("%d", ansMap[i][j]);                }                printf("\n");            }         }    }    return 0;}