FZU 1686神龙的难题 （重复覆盖）

题目链接：http://acm.fzu.edu.cn/problem.php?pid=1686

思路：

重复覆盖模板题。

1为列，可以操作的点为行

#include <stdio.h>#include <string.h>#include <iostream>#include <algorithm>#include <vector>#include <queue>#include <set>#include <map>#include <string>#include <math.h>#include <stdlib.h>#include <time.h>using namespace std;const int MaxM = 15*15+10;const int MaxN = 15*15+10;const int maxnode = MaxN * MaxM;const int INF = 0x3f3f3f3f;struct DLX{    int n,m,size;    int U[maxnode],D[maxnode],R[maxnode],L[maxnode],Row[maxnode],Col[maxnode];    int H[MaxN],S[MaxM];    int ansd;    void init(int _n,int _m)    {        n = _n;        m = _m;        for(int i = 0;i <= m;i++)        {            S[i] = 0;            U[i] = D[i] = i;            L[i] = i-1;            R[i] = i+1;        }        R[m] = 0; L[0] = m;        size = m;        for(int i = 1;i <= n;i++)H[i] = -1;    }    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)    {        for(int i = D[c];i != c;i = D[i])            L[R[i]] = L[i], R[L[i]] = R[i];    }    void resume(int c)    {        for(int i = U[c];i != c;i = U[i])            L[R[i]] = R[L[i]] = i;    }    bool v[MaxM];    int f()    {        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;    }    void Dance(int d)    {        if(d + f() >= ansd)return;        if(R[0] == 0)        {            if(d < ansd)ansd = d;            return;        }        int c = R[0];        for(int i = R[0];i != 0;i = R[i])            if(S[i] < S[c])                c = i;        for(int i = D[c];i != c;i = D[i])        {            remove(i);            for(int j = R[i];j != i;j = R[j])remove(j);            Dance(d+1);            for(int j = L[i];j != i;j = L[j])resume(j);            resume(i);        }    }};DLX g;int a[20][20];int id[20][20];int main(){    //freopen("in.txt","r",stdin);    //freopen("out.txt","w",stdout);    int n,m;    while(scanf("%d%d",&n,&m) == 2)    {        int sz = 0;        memset(id,0,sizeof(id));        for(int i = 0;i < n;i++)            for(int j = 0;j < m;j++)            {                scanf("%d",&a[i][j]);                if(a[i][j] == 1)id[i][j] = (++sz);            }        g.init(n*m,sz);        sz = 1;        int n1,m1;        scanf("%d%d",&n1,&m1);        for(int i = 0;i < n;i++)            for(int j = 0;j < m;j++)            {                for(int x = 0;x < n1 && i + x < n;x++)                    for(int y = 0;y < m1 && j + y < m;y++)                        if(id[i+x][j+y])                            g.Link(sz,id[i+x][j+y]);                sz++;            }        g.ansd = INF;        g.Dance(0);        printf("%d\n",g.ansd);    }    return 0;}