[Zjoi2006] short-circuit dynamic planning for logistics and transportation

Code:

The definition Status $ DP [I] $ is the minimum cost of the previous $ I $ days.

Status transfer: $ DP [I] = min (DP [I], DP [J] + spfa (J + 1, I) $ here $ spfa (I, j) $ refers to $ (I, j) $ the shortest path (minimum cost) in the day with the most short-circuit solution)

 

#include<cstdio>#include<algorithm>#include<cstring>#include<string>#include<deque>using namespace std;void setIO(string a){    freopen((a+".in").c_str(),"r",stdin);}const int maxn=30;const int inf=10000000;int n,m;int tag[maxn],head[maxn], to[1000000], nex[1000000],val[1000000],edges;int a[maxn][200];long long dp[200];void add_edge(int u,int v,int c){    nex[++edges]=head[u], head[u]=edges, to[edges]=v, val[edges]=c;}deque<int>Q;bool inq[100000];int d[maxn];int spfa(int l,int r){    Q.clear();    for(int i=0;i<maxn;++i) d[i]=inf;    memset(tag,0,sizeof(tag));    memset(inq,false,sizeof(inq));    for(int i=1;i<=m;++i)        for(int j=l;j<=r;++j)            if(a[i][j]) tag[i]=1;    Q.push_back(1);    d[1]=0,inq[1]=true;    while(!Q.empty()){        int u=Q.front();        Q.pop_front();        inq[u]=false;        for(int v=head[u];v;v=nex[v]){            if(tag[to[v]]) continue;            if(d[u]+val[v] < d[to[v]]){                d[to[v]]=d[u]+val[v];                if(!inq[to[v]]){                    if(Q.empty()||d[to[v]]<=d[Q.front()]) Q.push_front(to[v]);                    else Q.push_back(to[v]);                    inq[to[v]]=true;                }            }        }    }    return d[m];}void update(long long  &a,long long b){    if(b<a)a=b;}int main(){    //setIO("input");    int k,e;    scanf("%d%d%d%d",&n,&m,&k,&e);    for(int i=1;i<=e;++i){        int a,b,c;        scanf("%d%d%d",&a,&b,&c);        add_edge(a,b,c);        add_edge(b,a,c);    }    int cnt;    scanf("%d",&cnt);//    for(int i=1;i<=cnt;++i){        int p,l,r;        scanf("%d%d%d",&p,&l,&r);        for(int j=l;j<=r;++j) a[p][j]=1;    }    for(int i=1;i<=n;++i)    {        dp[i]=spfa(1,i)*i;        for(int j=1;j<i;++j)             update(dp[i],dp[j]+(long long)spfa(j+1,i)*(i-j)+k);    }    printf("%lld\n",dp[n]);    return 0;}

　　

[Zjoi2006] short-circuit dynamic planning for logistics and transportation