zoj 3209.Treasure Map（DLX精确覆盖）

#include <iostream>
#include <cstring>
#include <cstdio>
#include <cmath>
#include <vector>
using namespace std;

#define FOR(i,A,s)  for(int i = A[s]; i != s; i = A[i])
#define exp 1e-8

const int MAX = 510000;
int n, m, k, t, len;

struct DLX {
int n, Size;//Size为尾指针，真正大小
int row[MAX], col[MAX];//记录每个点的行列
int U[MAX], D[MAX], R[MAX], L[MAX]; //4个链表
int S[MAX],H[MAX];//每列1的个数
int ncnt, ans[MAX];
void init (int n) {
this->n = n;
ncnt = MAX;
//增加n+1个辅助链表，从0到n
for (int i = 0; i <= n; i++)
U[i] = D[i] = i, L[i] = i - 1, R[i] = i + 1,S[i]=0;
R
= 0, L[0] = n; //头尾相接
Size = n + 1;
memset (H, -1, sizeof H);
}
//单点添加
void Link (int r, int c)
{
++S[col[++Size] = c];
row[Size] = r;
D[Size] = D[c];
U[D[c]] = Size;
U[Size] = c;
D[c] = Size;
if (H[r] < 0) H[r] = L[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) {
//精确覆盖
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]];
//        //重复覆盖
//        for (int i = D[c]; i != c; i = D[i])
//            L[R[i]] = L[i], R[L[i]] = R[i];
}
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;
//重复覆盖
//        for (int i = U[c]; i != c; i = U[i])
//            L[R[i]] = R[L[i]] = i;
}
bool v[MAX];
int ff() {
int ret = 0;
for (int c = R[0]; c != 0; c = R[c]) v[c] = true;
for (int c = R[0]; c != 0; c = R[c])
if (v[c])
{
ret++;
v[c] = false;
for (int i = D[c]; i != c; i = D[i])
for (int j = R[i]; j != i; j = R[j])
v[col[j]] = false;
}
return ret;
}
bool dfs (int d) {
if (d >= ncnt) return 0;
//if (d + ff() > k) return 0;//重复覆盖
if (R[0] == 0) {
ncnt = min (ncnt, d);
return 1;
}
int c = R[0];
for (int i = R[0]; i != 0; i = R[i])
if (S[i] < S[c])
c = i;
Remove (c);//精确覆盖
FOR (i, D, c) {
//Remove (i);//重复覆盖
ans[d] = row[i];
FOR (j, R, i) Remove (col[j]);//精确覆盖
//FOR (j, R, i) Remove (j);//重复覆盖
//if (dfs (d + 1) ) return 1;
dfs (d + 1);
FOR (j, L, i) Restore (col[j]);//精确覆盖
//FOR (j, L, i) Restore (j);//重复覆盖
//Restore (i);//重复覆盖
}
Restore (c);//精确覆盖
return 0;
}
bool solve (vector<int> &v) {
v.clear();
if (!dfs (0) ) return 0;
for (int i = 0; i < ncnt; i++) v.push_back (ans[i]);
return 1;
}
} Dance;
int columns[31][31 * 31];
int main() {
scanf ("%d", &t);
while (t--) {
memset (columns, 0, sizeof columns);
scanf ("%d %d %d", &n, &m, &k);
len = n * m;
Dance.init (len);
int x,y,xx,yy;
for (int p = 1; p <= k; p++) {
scanf ("%d %d %d %d", &x, &y, &xx, &yy);
for (int i = x+1; i <= xx; i++)
for (int j = y+1; j <= yy; j++)
Dance.Link (p, j + (i-1)*m);
}
Dance.dfs (0);
printf ("%d\n", Dance.ncnt == MAX ? -1 : Dance.ncnt);
}
return 0;
}