hdu1426 Sudoku Killer

简单的DFS，将所有未填的位置依次保存起来，之后，对每一个未填的位置依次枚举，往下搜即可

；；

本来想用DLX的做的，hdu3111是过了，可是原先那个模板在这道题里就是超时，不解啊，换一个模板就过了、

#include<stdio.h>
struct point
{
    int x, y;
} p[81];
int num, flag, map[10][10];
int judge(int n, int k)
{
    int i, j, x, y;
    for(i = 0; i < 9; i++)
    {
        if(i != p[n].y && map[p[n].x][i] == k)
            return 0;
        if(i != p[n].x && map[i][p[n].y] == k)
            return 0;
    }
    x = p[n].x / 3 * 3;
    y = p[n].y / 3 * 3;
    for(i = 0; i < 3; i++)
        for(j = 0; j < 3; j++)
            if(map[x+i][y+j] == k && (i != p[n].x || j != p[n].y))
                return 0;
    return 1;
}
void dfs(int n)
{
    int i;
    if(n == num)
    {
        flag = 1;
        return;
    }
    for(i = 1; i < 10; i++)
    {
        if(judge(n, i))
        {
            map[p[n].x][p[n].y] = i;
            dfs(n + 1);
            if(flag)
                return;
            map[p[n].x][p[n].y] = 0;
        }
    }
    return;
}
int main()
{
    int i, j, t = 0;
    char s[2];
    while(scanf("%s", s) != -1)
    {
        num = flag = 0;
        if(s[0] == '?')
            p[num].x = 0, p[num++].y = 0, map[0][0] = 0;
        else
            map[0][0] = s[0] - '0';
        for(i = 0; i < 9; i++)
            for(j = 0; j < 9; j++)
                if(i || j)
                {
                    scanf("%s", s);
                    if(s[0] == '?')
                        p[num].x = i, p[num++].y = j, map[i][j] = 0;
                    else
                        map[i][j] = s[0] - '0';
                }
        dfs(0);
        if(t++)
            printf("\n");
        for(i = 0; i < 9; i++)
        {
            for(j = 0; j < 8; j++)
                printf("%d ", map[i][j]);
            printf("%d\n", map[i][8]);
        }
    }
    return 0;
}

#include<stdio.h>
#include<string.h>
#define INF 1000000000
const int N = 9;
const int mn = N * N * N *(N * N * N * 4) + N;
const int nn = N * N * N + N;
int U[mn], D[mn], L[mn], R[mn], C[mn], X[mn];
int H[nn], Q[nn], S[nn], vis[nn], size;
int a[nn][nn], ans[nn][nn];
void prepare(int r, int c)
{
    int i;
    for(i = 0; i <= c; i ++)
    {
        S[i] = 0;
        U[i] = D[i] = i;
        R[i] = i + 1;
        L[i + 1] = i;
    }
    R[c] = 0;
    size = c;
    while(r)
        H[r --] = -1;
}
void place(int &r, int &c1, int &c2, int &c3, int &c4, int i, int j, int k)
{
    r = (i * N + j) * N + k;
    c1 = i * N + j + 1;
    c2 = N * N + i * N + k;
    c3 = 2 * N * N + j * N + k;
    c4 = 3 * N * N + ((i / 3) * 3 + j / 3) * N + k;
}
void link(int r, int c)
{
    size ++;
    C[size] = c;
    S[c] ++;
    X[size] = r;
    D[size] = D[c];
    U[D[c]] = size;
    U[size] = c;
    D[c] = size;
    if(H[r] < 0)
    {
        H[r] = size;
        L[size] = size;
        R[size] = size;
    }
    else
    {
        R[size] = R[H[r]];
        L[R[H[r]]] = size;
        L[size] = H[r];
        R[H[r]] = size;
    }
}
void remove(int c)
{
    int i, j;
    L[R[c]] = L[c];
    R[L[c]] = R[c];
    for(i = D[c]; i != c; i = D[i])
        for(j = R[i]; j != i; j = R[j])
        {
            U[D[j]] = U[j];
            D[U[j]] = D[j];
            S[C[j]] --;
        }
}
void resume(int c)
{
    int i, j;
    for(i = U[c]; i != c; i = U[i])
        for(j = L[i]; j != i; j = L[j])
        {
            U[D[j]] = j;
            D[U[j]] = j;
            S[C[j]] ++;
        }
    R[L[c]] = c;
    L[R[c]] = c;
}
int dance(int cur)
{
    int i, j, c, temp;
    if(!R[0])
    {
        for(i = 0; i < cur ;i ++)
        {
            int x = (X[Q[i]] - 1) / N / N;
            int y = (X[Q[i]] - 1) / N % N;
            ans[x][y] = (X[Q[i]] - 1) % N + 1;
        }
        return 1;
    }
    temp = INF;
    for(i = R[0]; i != 0; i = R[i])
        if(S[i] < temp)
        {
            temp = S[i];
            c = i;
        }
    remove(c);
    for(i = D[c]; i != c; i = D[i])
    {
        Q[cur] = i;
        for(j = R[i] ; j != i; j = R[j])
            remove(C[j]);
        if(dance(cur + 1))
            return 1;
        for(j = L[i]; j != i; j = L[j])
            resume(C[j]);
    }
    resume(c);
    return 0;
}
int init()
{
    int i, j, k, r, c1, c2, c3, c4;
    char temp[5];
    if(scanf("%s", temp) != 1)
        return 0;
    a[0][0] = (temp[0] == '?' ? 0 : temp[0] - '0');
    for(i = 0; i < N; i ++)
        for(j = 0; j < N; j ++)
        {
            if(!i && !j)
                continue;
            scanf("%s", temp);
            a[i][j] = (temp[0] == '?' ? 0 : temp[0] - '0');
        }
    prepare(N * N * N, N * N * 4);
    memset(vis, 0, sizeof(vis));
    for(i = 0; i < N; i ++)
        for(j = 0; j < N; j ++)
            if(a[i][j])
            {
                place(r, c1, c2, c3, c4, i, j, a[i][j]);
                link(r, c1), link(r, c2), link(r, c3), link(r, c4);
                vis[c2] = vis[c3] = vis[c4] = 1;
            }
    for(i = 0; i < N; i ++)
        for(j = 0; j < N; j ++)
            if(!a[i][j])
                for(k  = 1; k <= N; k ++)
                {
                    place(r, c1, c2, c3, c4, i, j, k);
                    if(vis[c2] || vis[c3] || vis[c4])
                        continue;
                    link(r, c1), link(r, c2), link(r, c3), link(r, c4);
                }
    return 1;
}
void printresult()
{
    int i, j;
    for(i = 0; i < N; i ++)
    {
        for(j = 0; j < N; j ++)
        {
            if(j)
                printf(" ");
            printf("%d", ans[i][j]);
        }
        printf("\n");
    }
}
int main()
{
    int t = 0;
    while(init())
    {
        dance(0);
        if(t ++)
            printf("\n");
        printresult();
    }
    return 0;
}