2019HDU多校 Round3

09 K Subsequence

#include  <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int INF = 0x3f3f3f3f;

ll mincost;
int n, m, cnt, s, t, ts;
struct node {
    int to, nex, val, cost;
}E[4012005];
int head[4005];
int cur[4005];

void addedge(int u, int v, int va, int co) {
    E[++cnt].to = v; E[cnt].nex = head[u]; head[u] = cnt; E[cnt].val = va; E[cnt].cost = co;
    E[++cnt].to = u; E[cnt].nex = head[v]; head[v] = cnt; E[cnt].val = 0; E[cnt].cost = -co;
}

struct no1 {
    int to, edge;
}pre[4005];

int dis[4005];
bool inque[4005];
int que[4000005];
bool spfa() {
    for(int i = 1; i <= t; i++) dis[i] = INF, inque[i] = 0, cur[i] = head[i];
    dis[s] = 0; inque[s] = 1;
    int top = 0;
    que[++top] = s;

    while(top) {
        int u = que[top];
        top--;
        inque[u] = 0;

        for(int i = head[u]; i; i = E[i].nex) {
            int v = E[i].to;
            if(E[i].val && dis[v] > dis[u] + 1LL * E[i].cost) {
                dis[v] = dis[u] + 1LL * E[i].cost;
                pre[v].to = u;
                pre[v].edge = i;
                if(!inque[v]) {
                    inque[v] = 1;
                    que[++top] = v;
                }
            }
        }
    }
    return dis[t] != INF;
}

int ans, cos1;
void EK() {
    ans = cos1 = 0;

    while(spfa()) {
        int mi = INF;
        for(int i = t; i != s; i = pre[i].to) {
            mi = min(mi, E[pre[i].edge].val);
        }
        for(int i = t; i != s; i = pre[i].to) {
            E[pre[i].edge].val -= mi;
            E[pre[i].edge ^ 1].val += mi;
        }
        //for(int i = 1; i <= n; i++) h[i] += dis[i];
        ans += mi;
        cos1 += mi * dis[t];
    }
}

/*
ll h[4005];
ll dis[4005];
bool vvis[4005];
bool dij() {
    for(int i = 1; i <= t; i++) dis[i] = INF, cur[i] = head[i], vvis[i] = 0;
    dis[s] = 0;
    priority_queue< pair<int, int> > que;
    que.push(make_pair(0, s));

    while(!que.empty()) {
        int u = que.top().second;
        que.pop();

        if(vvis[u]) continue;
        vvis[u] = 1;

        for(int i = head[u]; i; i = E[i].nex) {
            int v = E[i].to;
            if(E[i].val && dis[v] + h[v] > dis[u] + 1LL * E[i].cost + h[u]) {
                dis[v] = dis[u] + 1LL * E[i].cost + h[u] - h[v];
                que.push(make_pair(-dis[v], v));
            }
        }
    }
    return dis[t] != INF;
}*/

int q[2005];
int main() {
    int T;
    scanf("%d", &T);
    while(T--) {
        scanf("%d%d", &n, &m);
        cnt = 1;
        memset(head, 0, sizeof(head));
        for(int i = 1; i <= n; i++) scanf("%d", &q[i]);
        s = n * 2 + 1;
        ts = s + 1;
        t = ts + 1;
        for(int i = 1; i <= n; i++) {
            for(int j = i + 1; j <= n; j++) {
                if(q[i] <= q[j]) addedge(i + n, j, 1, 0);
            }
        }

        for(int i = 1; i <= n; i++) addedge(s, i, 1, 0), addedge(i + n, ts, 1, 0), addedge(i, i + n, 1, -q[i]);
        addedge(ts, t, m, 0);

        EK();
        printf("%d\n", -cos1);
    }
    return 0;
}
/*
1
9 2
5 3 2 1 4 2 1 4 6
*/

K Subsequence