【POJ】3076 Sudoku

DLX第一题，模板留念。

/* 3076 */
#include <iostream>
#include <string>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <vector>
#include <deque>
#include <algorithm>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <climits>
#include <cctype>
#include <cassert>
#include <functional>
#include <iterator>
#include <iomanip>
using namespace std;
//#pragma comment(linker,"/STACK:102400000,1024000")

#define sti                set<int>
#define stpii            set<pair<int, int> >
#define mpii            map<int,int>
#define vi                vector<int>
#define pii                pair<int,int>
#define vpii            vector<pair<int,int> >
#define rep(i, a, n)     for (int i=a;i<n;++i)
#define per(i, a, n)     for (int i=n-1;i>=a;--i)
#define clr                clear
#define pb                 push_back
#define mp                 make_pair
#define fir                first
#define sec                second
#define all(x)             (x).begin(),(x).end()
#define SZ(x)             ((int)(x).size())
#define lson            l, mid, rt<<1
#define rson            mid+1, r, rt<<1|1



typedef struct DLX {
    static const int maxc = 4*16*16 + 5;
    static const int maxr = 16*16*16 + 5;
    static const int maxnode = 16*16*16*4 + 5;
    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 = n_;

        for (int i=0; i<=n; ++i) {
            L[i] = i - 1;
            R[i] = i + 1;
            U[i] = i;
            D[i] = i;
        }
        L[0] = n;
        R[n] = 0;

        sz = n + 1;
        memset(S, 0, sizeof(S));
    }

    void addRow(int r, vi columns) {
        int first = sz;
        int size = SZ(columns);

        for (int i=0; i<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;
    }

    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[col[j]];
            }
        }
    }

    void restore(int c) {
        for (int i=U[c]; i!=c; i=U[i]) {
            for (int j=L[i]; j!=i; j=L[j]) {
                ++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 (int i=R[0]; i!=0; i=R[i]) {
            if (S[i] < S[c])
                c = i;
        }

        remove(c);
        for (int i=D[c]; i!=c; i=D[i]) {
            ans[d] = row[i];
            for (int j=R[i]; j!=i; j=R[j]) {
                remove(col[j]);
            }
            if (dfs(d+1))    return true;
            for (int j=L[i]; j!=i; j=L[j]) {
                restore(col[j]);
            }
        }
        restore(c);

        return false;
    }

    bool solve(vector<int>& v) {
        v.clr();

        if (!dfs(0))    return false;

        for (int i=0; i<ansd; ++i)
            v.pb(ans[i]);

        return true;
    }
} DLX;

DLX solver;
const int SLOT = 0;
const int ROW = 1;
const int COL = 2;
const int SUB = 3;

int encode(int a, int b, int c) {
    return a*256+b*16+c+1;
}

void decode(int code, int& a, int& b, int& c) {
    --code;
    c = code%16;
    code /= 16;
    b = code%16;
    code /= 16;
    a = code;
}

char puzzle[16][20];

bool read() {
    rep(i, 0, 16)
        if (scanf("%s", puzzle[i])!=1)
            return false;
    return true;
}

int main() {
    ios::sync_with_stdio(false);
    #ifndef ONLINE_JUDGE
        freopen("data.in", "r", stdin);
        freopen("data.out", "w", stdout);
    #endif

    int kase = 0;
    
    while (read()) {
        if (kase++)
            putchar('
');
        
        solver.init(1024);
        rep(r, 0, 16) {
            rep(c, 0, 16) {
                rep(v, 0, 16) {
                    if (puzzle[r][c]=='-' || puzzle[r][c]=='A'+v) {
                        vi columns;
                        columns.pb(encode(SLOT, r, c));
                        columns.pb(encode(ROW, r, v));
                        columns.pb(encode(COL, c, v));
                        columns.pb(encode(SUB, r/4*4+c/4, v));
                        solver.addRow(encode(r, c, v), columns);
                    }
                }
            }
        }

        vi ans;
        bool flag = solver.solve(ans);
        #ifndef ONLINE_JUDGE
            puts(flag ? "Yes":"No");
        #endif
        int sz = SZ(ans);

        rep(i, 0, sz) {
            int r, c, v;
            decode(ans[i], r, c, v);
            puzzle[r][c] = v + 'A';
        }

        rep(i, 0, 16)
            puts(puzzle[i]);
    }
    
    #ifndef ONLINE_JUDGE
        printf("time = %d.
", (int)clock());
    #endif

    return 0;
}