ZOJ 3209 Treasure Map DLX

来源：互联网发布：淘宝差评能追评吗编辑：程序博客网时间：2024/06/05 18:51

用最少的矩阵覆盖n*m的地图，注意矩阵不能互相覆盖。

这里显然是一个精确覆盖，但由于矩阵拼接过程中，有公共的边，这里需要的技巧就是把矩阵的左边和下面截去一个单位。

#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>#include <assert.h>using namespace std;const int maxnode = 550005;const int MaxM = 999;const int MaxN = 555;int K,n,m;void print(int x){    printf("(%d %d)\n",x%(n+1)==0?n:(x%(n+1)-1),x%(n+1)==0?x/(n+1)-1:x/(n+1));}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 ands,ans[MaxN],ANS;    void init(int _n,int _m)    {        ANS=0x3f3f3f3f;        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)    {        int i,j;        L[R[c]]=L[c];        R[L[c]]=R[c];        for(i=D[c]; i!=c; i=D[i])        {            for(j=R[i]; j!=i; j=R[j])            {                U[D[j]]=U[j],D[U[j]]=D[j];                S[Col[j]]--;            }        }    }    void resume(int c)    {        int i,j;        for(i=U[c]; i!=c; i=U[i])        {            for(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 v[maxnode];    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()>=ANS) return;        if(R[0] == 0)        {            ANS=min(ANS,d);            return;        }        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])        {            for(int j = R[i]; j != i; j = R[j])remove(Col[j]);            Dance(d+1);            for(int j = L[i]; j != i; j = L[j])resume(Col[j]);        }        resume(c);    }} g;int main(){    int cas,x1,y1,x2,y2,k;    scanf("%d",&cas);    while(cas--)    {        scanf("%d%d%d",&n,&m,&k);        g.init(k,n*m);        for(int q=1; q<=k; q++)        {            scanf("%d%d%d%d",&x1,&y1,&x2,&y2);            for(int i = x1+1; i <= x2; i++)                for(int j = y1+1; j <= y2; j++)                    g.Link(q,j+(i-1)*m);        }        g.Dance(0);        if(g.ANS==0x3f3f3f3f) g.ANS=-1;        printf("%d\n",g.ANS);    }    return 0;}

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