hdu 3111 Sudoku

精確覆蓋DLX，模板

//#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<algorithm>
#include<iostream>
#include<cstring>
#include<cstdio>
#include<vector>
#include<string>
#include<queue>
#include<cmath>
#include<stack>
#include<set>
#include<map>
#define FIR first
#define SEC second
#define LL long long
#define MP make_pair
#define INF 0x3f3f3f3f
#define ULL unsigned long long
#define CLR(a, b) memset(a, b, sizeof(a))

using namespace std;

const int maxc = 1010;
const int maxr = 500;
const int maxnode = maxc*maxr;
struct DLX {
    int n, sz;
    int S[maxc];
    int row[maxnode], col[maxnode];
    int L[maxnode], R[maxnode], U[maxnode], D[maxnode];
    int ansd, ans[maxr];
    void init(int n) { ///n是列數
        this->n = n;
        for(int i = 0; i <= n; i ++) {
            U[i] = i, D[i] = i;
            L[i] = i - 1, R[i] = i + 1;
        }
        R[n] = 0; L[0] = n;
        sz = n + 1;
        CLR(S, 0);
    }
    void addRow(int r, vector<int> columns) {
        int first = sz;
        for(int i = 0; i < columns.size(); i ++) {
            int c = columns[i];
            L[sz] = sz - 1; R[sz] = sz + 1;
            D[sz] = c; U[sz] = U[c];
            D[U[c]] = sz; U[c] = sz;
            row[sz] = r; col[sz] = c;
            S[c] ++; sz ++;
        }
        R[sz - 1] = first; L[first] = sz - 1;
    }
#define FOR(i, A, s) for(int i = A[s]; i != s; i = A[i])
    void remove(int c) {
        L[R[c]] = L[c];
        R[L[c]] = R[c];
        FOR(i, D, c)
        FOR(j, R, i) {
            U[D[j]] = U[j];
            D[U[j]] = D[j];
            -- S[col[j]];
        }
    }

    void restore(int c) {
        FOR(i, U, c)
        FOR(j, L, i) {
            ++ S[col[j]];
            U[D[j]] = j;
            D[U[j]] = j;
        }
        L[R[c]] = c;
        R[L[c]] = c;
    }
    bool dfs(int d) {
        if(R[0] == 0) {
            ansd = d;
            return true;
        }
        int c = R[0];
        FOR(i, R, 0) if(S[i] < S[c]) c = i;
        remove(c);
        FOR(i, D, c) {
            ans[d] = row[i];
            FOR(j, R, i) remove(col[j]);
            if(dfs(d + 1)) return true;
            FOR(j, L, i) restore(col[j]);
        }
        restore(c);
        return false;
    }
    bool solve(vector<int>& v) {
        v.clear();
        if(!dfs(0)) return false;
        for(int i = 0 ; i < ansd; i ++) v.push_back(ans[i]);
        return true;
    }
} sol;

char ch[20][20];

int main() {
    int T;
    scanf("%d", &T);
    while(T --) {
        gets(ch[10]);
        for(int i = 0; i < 9; i ++)
            gets(ch[i]);
        sol.init(9*9*4);
        for(int i = 0; i < 9; i ++) {
            for(int j = 0; j < 9; j ++) {
                for(int k = 0; k < 9; k ++) {
                    if(ch[i][j] == '?' || ch[i][j] == k + '1') {
                        vector<int> v; v.clear();
                        int tmp = i * 9 + j + 1;
                        v.push_back(tmp);
                        tmp = 81 + i * 9 + k + 1;
                        v.push_back(tmp);
                        tmp = 81 * 2 + j * 9 + k + 1;
                        v.push_back(tmp);
                        tmp = 81 * 3 + (i / 3 * 3 + j / 3) * 9 + k + 1;
                        v.push_back(tmp);
                        sol.addRow(i * 81 + j * 9 + k + 1, v);
                    }
                }
            }
        }
        vector<int> ans;
        ans.clear();
        if(!sol.solve(ans)) puts("impossible");
        else {
            for(int i = 0; i < ans.size(); i ++) {
                ans[i] --;
                ch[ans[i] / 81][(ans[i] / 9) % 9] = ans[i] % 9 + '1';
            }
            for(int i = 0; i < 9; i ++)
                puts(ch[i]);
        }
        if(T) puts("---");
    }
}