【BZOJ】【P3265】【志愿者招募加强版】【题解】【单纯形法】

传送门：http://www.lydsy.com/JudgeOnline/problem.php?id=3265

读了一天算导，成功yy出单纯形~~

Code：

#include<bits/stdc++.h>
using namespace std;
const int maxn=10010;
const int maxm=1010;
const double eps=1e-8;
double a[maxn][maxm];
int n,m;
int dcmp(double x){
	if(fabs(x)<eps)return 0;
	return x>0?1:-1;
}
double simplex(bool f);
void pivot(int l,int e,bool f){
	for(int i=0;i<=m+f;i++){
		if(i==e)continue;
		a[l][i]/=a[l][e];
	}a[l][e]=1/a[l][e];
	for(int i=0;i<=n+f;i++){
		if(i==l)continue;
		for(int j=0;j<=m+f;j++){
			if(j==e)continue;
			a[i][j]-=a[i][e]*a[l][j];
		}a[i][e]*=-a[l][e];
	}
}
void init(){
	int pos=-1;
	double minn=1e10;
	for(int i=1;i<=n;i++)
	if(dcmp(minn-a[i][0])==1)minn=a[i][0],pos=i;
	if(dcmp(minn)>=0)return;
	for(int i=0;i<=m;i++)swap(a[0][i],a[n+1][i]);
	for(int i=0;i<=n;i++)a[i][m+1]=-1;
	pivot(pos,m+1,1);
	if(!dcmp(simplex(1))){
		for(int i=1;i<=m+1;i++)if(!dcmp(a[0][i]+1)){pos=i;break;}
		for(int i=0;i<=m+1;i++)swap(a[0][i],a[n+1][i]);
		for(int i=0;i<=n+1;i++)swap(a[i][pos],a[i][m+1]);
	}else puts("Can't solve!!");
}
double simplex(bool f){
	for(;;){
		int pos=-1,l,e;
		double minn=0;
		for(int i=1;i<=m+f;i++)
		if(dcmp(a[0][i]-minn)==1)minn=a[0][i],pos=i;
		if(!~pos)return -a[0][0];
		e=pos;pos=-1;minn=1e10;
		for(int i=1;i<=n;i++)
		if(dcmp(a[i][e])==1&&dcmp(a[i][0]/a[i][e]-minn)==-1)
		minn=a[i][0]/a[i][e],pos=i;
		if(!~pos){
			printf("INF!!\n");
			return 1e10;
		}l=pos;
		pivot(l,e,f);
	}
}
int main(){
	scanf("%d%d",&m,&n);
	for(int i=1;i<=m;i++)scanf("%lf",&a[0][i]);
	for(int i=1;i<=n;i++){
		int k;scanf("%d",&k);
		while(k--){
			int l,r;scanf("%d%d",&l,&r);
			for(int j=l;j<=r;j++)a[i][j]=1;
		}scanf("%d",&k);
		a[i][0]=k;
	}
	init();
	int ans=simplex(0)+.5;
	printf("%d\n",ans);
	return 0;
}