HDU 4069 Squiggly Sudoku【Dancing Links精确覆盖】

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;
}

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HDU 4069 Squiggly Sudoku【Dancing Links精确覆盖】

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