UVALive 2659 数独 DLX模板

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <string>
#include <queue>
#include <stack>
#include <vector>
#include <map>
#include <set>
#include <functional>
#include <cctype>
#include <time.h>

using namespace std;

const int INF = 1<<30;
const int MAXN = 1055;
const int MAXNODE = 16555;
const int MAXR = 1055;

struct DLX {
// 行编号从1开始，列编号为1~n，结点0是表头结点；结点1~n是各列顶部的虚拟结点
int n, sz; // 列数，结点总数
int S[MAXN]; //各列结点数

int row[MAXNODE], col[MAXNODE]; //各结点行列编号
int L[MAXNODE], R[MAXNODE], U[MAXNODE], D[MAXNODE]; //十字链表

int ansd, ans[MAXR]; // 解

void init(int n)  { //n是列数
this->n = n;

//虚拟结点
for (int i = 0; i <= n; i++) {
U[i] = i; D[i] = i; L[i] = i-1; R[i] = i+1;
}
R
= 0; L[0] = n;
sz = n+1;
memset(S, 0, sizeof(S));
}

void addRow(int r, vector<int> columns) {
//这一行的第一个结点
//行没有设头结点，每一行连成一个环形
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;
}

//顺着链表A，遍历s外的其他元素
#define FOR(i, A, s) for (int i = A[s]; i != s; i = A[i])

void remove(int c) { //删除c列
L[R[c]] = L[c]; R[L[c]] = R[c];
for (int i = D[c]; i != c; i = D[i]) // 对于每一个c列不为0的所有行
for (int j = R[i]; j != i; j = R[j]) { //删除这一整行
U[D[j]] = U[j]; D[U[j]] = D[j]; S[col[j]]--;
}
}

void restore(int c) { //回连c列
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[col[j]]++;
}
L[R[c]] = c; R[L[c]] = c;
}

bool dfs(int d) { //d为递归深度
if (R[0] == 0) { //找到解
ansd = d; //记录解的长度
return true;
}

//找S最小的C列
int c = R[0]; //第一个未删除的列
for (int i = R[0]; i != 0; i = R[i]) if (S[i]<S[c]) c = i;

remove(c); //删除第c列
for (int i = D[c]; i != c; i = D[i]) { //用结点i所在的行覆盖第c列
ans[d] = row[i];
for (int j = R[i]; j != i; j = R[j]) remove(col[j]); //删除节结点i所在行覆盖第c列
if (dfs(d+1)) return true;
for (int j = L[i]; j != i; j = L[j]) restore(col[j]); // 恢复
}
restore(c); //恢复
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;
}
};

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

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

inline 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() {
for (int i = 0; i < 16; i++)
if (scanf("%s", puzzle[i])!=1) return false;
return true;
}

DLX solver;

int main() {
#ifdef Phantom01
freopen("LA2659.txt", "r", stdin);
#endif //Phantom01

int T= 0;

while (read()) {
if (T!=0) puts(""); T++;
solver.init(1024);
for (int r = 0; r < 16; r++)
for (int c = 0; c < 16; c++)
for (int v = 0; v < 16; v++)
if (puzzle[r][c]=='-'|| puzzle[r][c]=='A'+v) {
vector<int> columns;
columns.push_back(encode(SLOT, r, c));
columns.push_back(encode(ROW, r, v));
columns.push_back(encode(COL, c, v));
columns.push_back(encode(SUB, (r/4)*4+c/4, v));
solver.addRow(encode(r, c, v), columns);
}
vector<int> ans;
if (!solver.solve(ans)) while (1) ;

for (int i = 0; i < ans.size(); i++) {
int r, c, v;
decode(ans[i], r, c, v);
puzzle[r][c] = 'A'+v;
}
for (int i = 0; i < 16; i++) {
printf("%s\n", puzzle[i]);
}
}

return 0;
}