# 【UOJ#179】线性规划 单纯形

## Code

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<vector>
using namespace std;
#define eps 1e-9
{
int x=0,f=1; char ch=getchar();
while (ch<'0' || ch>'9') {if (ch=='-') f=-1; ch=getchar();}
while (ch>='0' && ch<='9') {x=x*10+ch-'0'; ch=getchar();}
return x*f;
}

int N,M,id[11000];
double a[1100][1100],c[1100],b[1100],v,ans[1100];
inline void Pivot(int l,int e)
{
swap(id[e],id[N+l]);

double r=a[l][e];

a[l][e]=1;
for (int i=1; i<=N; i++) a[l][i]/=r;
b[l]/=r;

for (int i=1; i<=M; i++)
if (i!=l) {
r=a[i][e];

a[i][e]=0,b[i]-=r*b[l];
for (int j=1; j<=N; j++) a[i][j]-=r*a[l][j];
}

r=c[e];
c[e]=0;
for (int i=1; i<=N; i++) c[i]-=r*a[l][i];

v+=r*b[l];
}

inline int Simplex()
{
int l,e; double k;
while (1) {
l=e=0; k=-eps;
for (int i=1; i<=M; i++)
if (b[i]<k) k=b[i],l=i;
if (!l) break;
k=-eps;
for (int i=1; i<=N; i++)
if (a[l][i]<k && (!e || (rand()&1))) k=a[l][i],e=i;
if (!e) {puts("Infeasible"); return 1;}
Pivot(l,e);
}
while (1) {
for (int i=1; i<=N; i++) {
if (c[i]>eps) {e=i; break;}
if (i==N) {printf("%.8lf\n",v); return 0;}
}
double re=1e18; l=0;

for (int i=1; i<=M; i++)
if (a[i][e]>eps && b[i]/a[i][e]<re)
re=b[i]/a[i][e],l=i;

if (!l) {puts("Unbounded"); return 2;}
Pivot(l,e);
}

}

int main()
{

for (int i=1; i<=N; i++) scanf("%lf",&c[i]),id[i]=i;
for (int i=1; i<=M; i++) {
for (int j=1; j<=N; j++) scanf("%lf",&a[i][j]);
scanf("%lf",&b[i]);
}

int flag=Simplex();

if (flag || !type) return 0;

for (int i=1; i<=M; i++) ans[id[N+i]]=b[i];
for (int i=1; i<=N; i++) printf("%.8lf ",ans[i]);

return 0;
}


——It's a lonely path. Don't make it any lonelier than it has to be.
posted @ 2017-03-08 15:45  DaD3zZ  阅读(442)  评论(0编辑  收藏  举报