Cod sursa(job #2705084)

Utilizator cyg_SerbanBFlorin Gheorghe cyg_SerbanB Data 11 februarie 2021 21:05:14
Problema Flux maxim Scor 70
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 2.1 kb
#include <bits/stdc++.h>
#define min(a,b) a<b? a: b
using namespace std;
const int inf=INT_MAX;
const int nmax=5005;
struct edge
{
    int x,y;
    long long f,c;
};
int n,m,st,dr,lvl[nmax],viz[nmax];
long long lim,flow;
vector<edge> mch;
vector<int> adc[nmax];
queue<int> q;
void addedge(int x,int y,int c)
{
    edge temp;

    temp.x=x;
    temp.y=y;
    temp.c=c;
    temp.f=0;
    adc[x].push_back(mch.size());
    mch.push_back(temp);

    temp.x=y;
    temp.y=x;
    temp.c=0;
    temp.f=0;
    adc[y].push_back(mch.size());
    mch.push_back(temp);
}
bool bfs()
{
    while(!q.empty())
    {
        int nod=q.front();
        q.pop();
        for(int i=0; i<adc[nod].size(); ++i)
            if((mch[adc[nod][i]].c-mch[adc[nod][i]].f>=1) && (lvl[mch[adc[nod][i]].y]==-1))
            {
                lvl[mch[adc[nod][i]].y]=lvl[nod]+1;
                q.push(mch[adc[nod][i]].y);
            }
    }
    return lvl[dr]!=-1;
}
int dfs(int nod,int f)
{
    if(nod==dr)
        return f;
    for(int i=viz[nod];i<adc[nod].size();++i)
    {
        int u = mch[adc[nod][i]].y;
        if(lvl[nod]+1!=lvl[mch[adc[nod][i]].y] || mch[adc[nod][i]].c-mch[adc[nod][i]].f<1)
            continue;
        long long ret=dfs(mch[adc[nod][i]].y,min(f,mch[adc[nod][i]].c-mch[adc[nod][i]].f));
        if(ret==0)
            continue;
        mch[adc[nod][i]].f+=ret;
        mch[adc[nod][i] ^ 1].f-=ret;
        return ret;
    }
    return 0;
}
long long flux()
{
    flow=0;
    while(1)
    {
        for(int i=0; i<=n; ++i)
            lvl[i]=-1;
        lvl[st]=0;
        q.push(st);
        if(!bfs())
            break;
        for(int i=0; i<=n; ++i)
            viz[i]=0;
        while(long long ret=dfs(st,inf))
            flow+=ret;
    }
    return flow;
}
int main()
{
    freopen("maxflow.in","r",stdin);
    freopen("maxflow.out","w",stdout);
    scanf("%d%d",&n,&m);
    for(int i=1;i<=m;++i)
    {
        int  x,y,c;
        scanf("%d%d%d",&x,&y,&c);
        addedge(x,y,c);
    }
    st=1;dr=n;
    printf("%lld",flux());
    return 0;
}