tags：没搞懂，单纯形法，很数学的感觉。。但又学到一个模板=^=，MDZZ

#include
     
      #include
      
       using namespace std;#pragma comment(linker, "/STACK:102400000,102400000")#define rep(i,a,b) for (int i=a;i<=b;i++)#define per(i,b,a) for (int i=b;i>=a;i--)#define mes(a,b)  memset(a,b,sizeof(a))#define INF 0x3f3f3f3ftypedef long long ll;const int N=1010, M=10010;const double inf=1e10, eps=1e-7;int n, m;double b[M], c[N], cof[M][N], ans;void pivot(int id, int pos){    b[id]/=cof[id][pos];    cof[id][pos]=1/cof[id][pos];    for(int i=1; i<=n; i++) if(i!=pos) cof[id][i]*=cof[id][pos];    for(int i=1; i<=m; i++) if(i!=id && fabs(cof[i][pos])>eps) {        b[i]-=cof[i][pos]*b[id];        for(int j=1; j<=n; j++) if(j!=pos)            cof[i][j]-=cof[i][pos]*cof[id][j];        cof[i][pos]= -cof[i][pos]*cof[id][pos];    }    ans+=c[pos]*b[id];    for(int i=1; i<=n; i++) if(i!=pos) c[i]-=c[pos]*cof[id][i];    c[pos]= -c[pos]*cof[id][pos];}double simplex(){    while(1) {        int pos, id;        for(pos=1; pos<=n; pos++) if(c[pos]>eps) break;        if(pos==n+1) return ans;        double temp=inf;        for(int i=1; i<=m; i++) if(cof[i][pos]>eps && b[i]/cof[i][pos]