loj2031 "SDOI2016" Digital Matching

Run the maximum cost and maximum flow, and notice that the cost of each spfa must be less and less. When it is less than \(0\) , stop it.

#include <iostream>
#include <cstring>
#include <cstdio>
#include <queue>
using namespace std;
typedef long long ll;
int n, a[205], b[205], c[205], dd[205], hea[205], cnt, ss, tt, pre[205];
const int oo=0x3f3f3f3f;
bool vis[205];
ll dis[205], ans;
queue<int> d;
struct Edge{
    int too, nxt, val;
    ll cst;
}edge[200005];
int calc(int x){
    int re=0;
    for(int i=2; i*i<=x; i++)
        if(x%i==0){
            while(x%i==0){
                x /= i;
                re++;
            }
        }
    if(x!=1)    re++;
    return re;
}
void add_edge(int fro, int too, int val, ll cst){
    edge[cnt].nxt = hea[fro];
    edge[cnt].too = too;
    edge[cnt].val = val;
    edge[cnt].cst = cst;
    hea[fro] = cnt++;
}
void addEdge(int fro, int too, int val, ll cst){
    add_edge(fro, too, val, cst);
    add_edge(too, fro, 0, -cst);
}
bool spfa(){
    memset(dis, 0x3f, sizeof(dis));
    memset(pre, -1, sizeof(pre));
    d.push(ss);
    dis[ss] = 0;
    vis[ss] = true;
    while(!d.empty()){
        int x=d.front();
        d.pop();
        vis[x] = false;
        for(int i=hea[x]; i!=-1; i=edge[i].nxt){
            int t=edge[i].too;
            if(dis[t]>dis[x]+edge[i].cst && edge[i].val>0){
                dis[t] = dis[x] + edge[i].cst;
                pre[t] = i;
                if(!vis[t]){
                    vis[t] = true;
                    d.push(t);
                }
            }
        }
    }
    return dis[tt]!=0x3f3f3f3f3f3f3f3f;
}
void mcmf(){
    ll cost=0;
    while(spfa()){      int tmp=oo;
        for(int i=pre[tt]; i!=-1; i=pre[edge[i^1].too])
            tmp = min(tmp, edge[i].val);
        if(cost+(ll)tmp*dis[tt]<=0){
            cost += (ll)tmp * dis[tt];
            ans += tmp;
            for(int i=pre[tt]; i!=-1; i=pre[edge[i^1].too]){
                edge[i].val -= tmp;
                edge[i^1].val += tmp;
            }
        }
        else{
            ans += cost / (-dis[tt]);
            return ;
        }
    }
}
int main(){
    memset(hea, -1, sizeof(hea));
    cin>>n;
    for(int i=1; i<=n; i++) scanf("%d", &a[i]);
    for(int i=1; i<=n; i++) scanf("%d", &b[i]);
    for(int i=1; i<=n; i++) scanf("%d", &c[i]);
    for(int i=1; i<=n; i++) dd[i] = calc(a[i]);
    ss = 0; tt = n + 1;
    for(int i=1; i<=n; i++){
        if(dd[i]&1){
            addEdge(ss, i, b[i], 0);
            for(int j=1; j<=n; j++)
                if(a[j]%a[i]==0 && dd[j]==dd[i]+1)  addEdge(i, j, oo, (ll)-c[i]*c[j]);
                else if(a[i]%a[j]==0 && dd[i]==dd[j]+1) addEdge(i, j, oo, (ll)-c[i]*c[j]);
        }
        else    addEdge(i, tt, b[i], 0);
    }
    mcmf();
    printf("%lld\n", ans);
    return 0;
}

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