[国家集训队]墨墨的等式 [差分约束]

2371 [国家集训队]墨墨的等式

直接放学长的讲解还有代码算了.....

#include<iostream>
#include<cstdio>
#include<queue>
#include<cstring>
#include<cmath>
#include<stack>
#include<algorithm>
#define rg register
#define ll long long
#define LDB long double
#define ull unsigned long long
#define view(i,x) for(rg int i=hd[x];i!=-1;i=e[i].nt)
#define go(i,x,a) for(rg int i=a;i<x;i++)
#define inf 0x3f3f3f3f
#define INF 0x7fffffff
using namespace std;

const int maxn=5e5+5;
int n,hd[maxn],k,a[maxn],vis[maxn];
ll L,R,dis[maxn];
struct edd{
    int nt,v,w;
}e[maxn*20];

inline ll rd(){
    ll ret=0,af=1; char gc=getchar();
    while(gc < '0' || gc > '9'){ if(gc=='-') af=-af; gc=getchar(); }
    while(gc >= '0' && gc <= '9') ret=ret*10+gc-'0',gc=getchar();
    return ret*af;
}

inline void add(int a,int b,int c){
    e[k].v=b; e[k].w=c; e[k].nt=hd[a]; hd[a]=k++;
}

void spfa(){
    memset(dis,-1,sizeof(dis));
    deque<int>q;
    /*go(i,n+1,1){
        int x=a[i]%a[1];
        if(dis[x] == -1) dis[x]=a[i],q.push_back(x),vis[x]=1;
        else dis[x]=min(dis[x],(ll)a[i]);
    }*/
    q.push_back(0); vis[0]=1; dis[0]=0;
    while(!q.empty()){
        int x=q.front(); q.pop_front(); vis[x]=0;
        for(rg int i=hd[x];i!=-1;i=e[i].nt){
            int v=e[i].v,w=e[i].w;
            if(dis[v] == -1 || dis[v] > dis[x]+w){
                dis[v]=dis[x]+w;
                if(!vis[v]){
                    if(q.empty()) q.push_back(v);
                    else if(dis[v] < dis[q.front()]) q.push_front(v);
                         else q.push_back(v);
                    vis[v]=1;
                }
            }
        }
    }
}

inline ll cal(ll m){
    ll ans=0;
    go(i,a[1],0){
        if(dis[i] > m || dis[i] == -1) continue;
        ans=ans+(m-dis[i])/a[1]+1;
    }
    return ans;
}

int main(){
    #ifndef ONLINE_JUDGE
    freopen("3.in","r",stdin);
    //freopen(".out","w",stdout);
    #endif
    memset(hd,-1,sizeof(hd)); k=0;
    n=rd(); L=rd(); R=rd();
    go(i,n+1,1) a[i]=rd();
    sort(a+1,a+n+1);
    go(i,a[1],0)
        go(j,n+1,2) 
            add(i,(i+a[j])%a[1],a[j]);
    spfa();
    printf("%lld",cal(R)-cal(L-1));
    return 0;
}//Faze

 upd2019.9.16

#include<bits/stdc++.h>
using namespace std;
#define Max(x,y) ((x)>(y)?(x):(y))
#define Min(x,y) ((x)<(y)?(x):(y))
#define ll long long
const int N=12+10,M=500000+10,inf=0x3f3f3f3f;
int n,a[N];
ll b1,b2,ans=0;
template <class t>void rd(t &x){
    x=0;int w=0;char ch=0;
    while(!isdigit(ch)) w|=ch=='-',ch=getchar();
    while(isdigit(ch)) x=(x<<1)+(x<<3)+(ch^48),ch=getchar();
    x=w?-x:x;
}

int head[M],tot=0;
struct edge{int v,w,nxt;}e[M*20];
void add(int u,int v,int w){
    e[++tot]=(edge){v,w,head[u]},head[u]=tot;
}

queue<int>q;bool vis[M];
ll dis[M];
void spfa(){
    memset(dis,inf,sizeof(dis));
    memset(vis,0,sizeof(vis));
    q.push(0),vis[0]=1,dis[0]=0;
    while(!q.empty()){
        int u=q.front();q.pop(),vis[u]=0;
        for(int i=head[u],v,w;i;i=e[i].nxt)
        if(dis[v=e[i].v]>dis[u]+(w=e[i].w)){
            dis[v]=dis[u]+w;
            if(!vis[v]) q.push(v),vis[v]=1;
        }
    }
}

int main(){
    freopen("in.txt","r",stdin);
    rd(n),rd(b1),rd(b2);
    for(int i=1;i<=n;++i) rd(a[i]);
    sort(a+1,a+n+1);
    for(int i=0;i<a[1];++i)
        for(int j=2;j<=n;++j) add(i,(i+a[j])%a[1],a[j]);
    spfa();
    for(int i=0;i<a[1];++i){
        if(dis[i]<=b1-1) ans-=(b1-1-dis[i])/a[1]+1;
        if(dis[i]<=b2) ans+=(b2-dis[i])/a[1]+1;
    }
    printf("%lld",ans);
    return 0;
}