bzoj 2539: [Ctsc2000]丘比特的烦恼 （KM算法）

题目描述

传送门

题解

KM的裸题吧，就是细节比较恶心。。。。

代码

#include<iostream>#include<algorithm>#include<cstring>#include<cstdio>#include<cmath>#include<map>#define N 103#define inf 1000000000using namespace std;double dis,dx[N],dy[N],fx[N],fy[N]; int n,val[N][N],cx[N],cy[N],pdx[N],pdy[N],belong[N],slack[N];map<string,int> mp;string s,g,b;bool check(int ii,int jj){    double x=dx[ii],y=dy[ii],x1=fx[jj],y1=fy[jj];    if (x>x1) swap(x,x1),swap(y,y1);    for (int i=1;i<=n;i++)     if (dx[i]>=min(x,x1)&&dx[i]<=max(x,x1)&&dy[i]>=min(y,y1)&&dy[i]<=max(y,y1)){        if (ii==i) continue;        if (x==x1) return false;        double k=(dy[i]-y)/(dx[i]-x);         double k1=(y1-y)/(x1-x);        if (k==k1) return false;     }    for (int i=1;i<=n;i++)     if (fx[i]>=min(x,x1)&&fx[i]<=max(x,x1)&&fy[i]>=min(y,y1)&&fy[i]<=max(y,y1)){        if (i==jj) continue;        if (x==x1) return false;        double k=(fy[i]-y)/(fx[i]-x);         double k1=(y1-y)/(x1-x);        if (k==k1) return false;     }    return true;}bool dfs(int x){    pdx[x]=1;    for (int i=1;i<=n;i++){        if (pdy[i]) continue;        int gap=cx[x]+cy[i]-val[x][i];        if(!gap) {            pdy[i]=1;            if (!belong[i]||dfs(belong[i])) {                belong[i]=x;                return true;            }        }else slack[i]=min(gap,slack[i]);    }    return false;}int km(){    memset(belong,0,sizeof(belong));    memset(cy,0,sizeof(cy));    for (int i=1;i<=n;i++) {        cx[i]=val[i][1];        for (int j=1;j<=n;j++) cx[i]=max(cx[i],val[i][j]);    }    for (int i=1;i<=n;i++) {        for (int j=1;j<=n;j++) slack[j]=inf;        while (true) {            memset(pdx,0,sizeof(pdx));            memset(pdy,0,sizeof(pdy));            if(dfs(i)) break;            int d=inf;            for (int j=1;j<=n;j++)             if (!pdy[j]) d=min(d,slack[j]);            for (int j=1;j<=n;j++)             if (pdx[j]) cx[j]-=d;            for (int j=1;j<=n;j++)             if (pdy[j]) cy[j]+=d;             else slack[j]-=d;        }    }    int ans=0;    for (int i=1;i<=n;i++)      if (val[belong[i]][i]!=-inf) ans+=val[belong[i]][i];    return ans;}double pow(double x){ return x*x; }double getdis(double x,double y,double x1,double y1){ return sqrt(pow(x-x1)+pow(y-y1)); }int main(){    freopen("a.in","r",stdin);    scanf("%lf",&dis); scanf("%d",&n);    for (int i=1;i<=n;i++) {        cin>>dx[i]>>dy[i]>>s;        int l=s.length();        for (int j=0;j<l;j++)         if (s[j]>='A'&&s[j]<='Z') s[j]+=32;        mp[s]=i;    }    for (int i=1;i<=n;i++) {        cin>>fx[i]>>fy[i]>>s;        int l=s.length();        for (int j=0;j<l;j++)         if (s[j]>='A'&&s[j]<='Z') s[j]+=32;        mp[s]=i+n;    }    for(int i=1;i<=n;i++)     for (int j=1;j<=n;j++) val[i][j]=-inf;    while (true) {        int x;         cin>>g;        if (g=="End") break;        cin>>b>>x;        int l=g.length();        for (int k=0;k<l;k++)         if (g[k]>='A'&&g[k]<='Z') g[k]+=32;        l=b.length();        for (int k=0;k<l;k++)         if (b[k]>='A'&&b[k]<='Z') b[k]+=32;        int i=mp[g]; int j=mp[b];        if (i>j) swap(i,j); j-=n;        if (check(i,j)&&getdis(dx[i],dy[i],fx[j],fy[j])<=dis) val[i][j]=x;      }    for (int i=1;i<=n;i++)     for (int j=1;j<=n;j++)      if (i!=j&&check(i,j)&&getdis(dx[i],dy[i],fx[j],fy[j])<=dis) val[i][j]=max(val[i][j],1);    printf("%d\n",km());}