• https://darkbzoj.cc/problem/3550
• https://blog.bill.moe/bzoj3550-vacation/

const int N = int(1e4) + 9, M = int(1e3) + 9;

struct Simplex {
    DB a[N+1][M+1];
    int n, m;

    void pivot(int in, int out) {
        REP(i, m+1) if(i!=in) a[out][i] /= -a[out][in]; //重置out约束
        a[out][in] = 1/a[out][in];

        REP(i, n+1) if (i!=out && sgn(a[i][in])) { //重新计算其他约束
            DB t = a[i][in]; a[i][in] = 0;
            REP(j, m+1) a[i][j] += t*a[out][j];
        }
    }

    DB run() {
        while (true) {
            int in=0, out=0; DB Min=OO;
            REP_1(i, m) if(sgn(a[0][i])>0) {
                in=i;
                break;
            }
            if(!in)return a[0][0];
            REP_1(i, n) if(sgn(a[i][in])<0&&a[i][0]/-a[i][in]<Min) {
                Min=a[i][0]/-a[i][in];
                out=i;
            }
            if(!out)throw ; //unbounded
            pivot(in, out);
        }
    }

    int gao() {
        // z c
        // b A
        int n, k; RD(n, k); this->n = 5*n+1; m = 3*n;
        REP_1(i, 3*n) RD(a[0][i]);
        REP_1(i, 3*n) {
            a[i][0] = 1;
            a[i][i] = -1;
        }
        FOR_1(i, 3*n+1, 5*n+1) {
            REP(j, n) a[i][i-(3*n)+j] = -1;
            a[i][0] = k;
        }
        return run();
    }
} fst;

int main() {

#ifndef ONLINE_JUDGE
    freopen("in.txt", "r", stdin);
    //freopen("out.txt", "w", stdout);
#endif
    OT(fst.gao());
}

Posted by xiaodao
Category: 日常