CF 894E(Ralph and Mushrooms-Tarjen)

给一个有向图，每条边有边权w,第k次经过一条边获得max(0,w−1−2−..−(k−1)),问最大获得权值。
显然一个点强联通分量里的点可以一次取走，对原图缩点，跑DAG.

#include <iostream>#include <cmath>#include <algorithm>#include <cstdio>#include <cstring>#include <string>#include <vector>#include <map>#include <functional>#include <cstdlib>#include <queue>#include <stack>using namespace std;#define For(i,n) for(int i=1;i<=n;i++)#define Fork(i,k,n) for(int i=k;i<=n;i++)#define Rep(i,n) for(int i=0;i<n;i++)#define ForD(i,n) for(int i=n;i;i--)#define ForkD(i,k,n) for(int i=n;i>=k;i--)#define RepD(i,n) for(int i=n;i>=0;i--)#define Forp(x) for(int p=Pre[x];p;p=Next[p])#define Forpiter(x) for(int &p=iter[x];p;p=Next[p])  #define Lson (o<<1)#define Rson ((o<<1)+1)#define MEM(a) memset(a,0,sizeof(a));#define MEMI(a) memset(a,127,sizeof(a));#define MEMi(a) memset(a,128,sizeof(a));#define INF (2139062143)#define F (100000007)#define pb push_back#define mp make_pair #define fi first#define se second#define vi vector<int> #define pi pair<int,int>#define SI(a) ((a).size())typedef long long ll;typedef unsigned long long ull;ll mul(ll a,ll b){return (a*b)%F;}ll add(ll a,ll b){return (a+b)%F;}ll sub(ll a,ll b){return (a-b+llabs(a-b)/F*F+F)%F;}void upd(ll &a,ll b){a=(a%F+b%F)%F;}int read(){    int x=0,f=1; char ch=getchar();    while(!isdigit(ch)) {if (ch=='-') f=-1; ch=getchar();}    while(isdigit(ch)) { x=x*10+ch-'0'; ch=getchar();}    return x*f;} #define MAXN (2000010+10) vi G[MAXN];vector<ll> Gw[MAXN];int pre[MAXN],lowlink[MAXN],sccno[MAXN],dfs_clock,scc_cnt;stack<int> S; void dfs(int u) {    pre[u] = lowlink[u] = ++dfs_clock;    S.push(u);    int sz=SI(G[u]);    Rep(i,sz) {        int v=G[u][i];        if (!pre[v]) {            dfs(v);            lowlink[u]=min(lowlink[u],lowlink[v]);        } else if (!sccno[v]) {            lowlink[u]=min(lowlink[u],pre[v]);        }     }     if (lowlink[u]==pre[u]) {        scc_cnt++;          while(1) {            int x=S.top();S.pop();            sccno[x]=scc_cnt;            if (x==u) break;          }     }       } void find_scc(int n) {    dfs_clock = scc_cnt = 0;    MEM(sccno)     MEM(pre)    Rep(i,n) if (!pre[i]) dfs(i);}ll value[MAXN]={};ll calc(ll wei){    ll k=(long long)(sqrtl((long double)wei*2+0.25)-0.5);    return (k*(6*wei-(k+1)*(k+2)))/6+wei;}vi G2[MAXN];vector<ll> G2w[MAXN];ll f[MAXN];#define gmax(a,b) a=max(a,b)struct DFS{    int n,vis[MAXN];    vi e[MAXN];    bool b[MAXN];    void init(int n) {        memset(vis,0,sizeof(int)*(n+1));    }    void addedge(int u,int v) {        e[u].pb(v);     }    ll dfs(int s) {        if (vis[s]) return f[s];        f[s]=value[s];        Rep(i,SI(e[s])) {            gmax(f[s],dfs(e[s][i])+G2w[s][i]+value[s]);        }           vis[s]=1;        return f[s];    }}S1;int main() {//  freopen("E.in","r",stdin);    int n=read(),m=read();    For(i,m) {        int x=read(),y=read(),w=read();        x--,y--;        G[x].pb(y);        Gw[x].pb(w);    }    find_scc(n);    ll ans=0;    S1.init(scc_cnt);    Rep(i,n) {        Rep(j,SI(G[i])) {            int v=G[i][j];ll w=Gw[i][j];            if (sccno[i]==sccno[v]) {                if (w==0) continue;                ll totw=calc(w);                value[sccno[i]]+=totw;            }else {                S1.addedge(sccno[i],sccno[v]);                G2w[sccno[i]].pb(w);            }        }    }    int s=read();    s=sccno[--s];    S1.dfs(s);    cout<<f[s]<<endl;    return 0;}