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網路流板子

Dinic模板

#pragma GCC optimize(2)
#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 10;
//const int maxm = 1e3 * 2 + 10;
const int inf = 0x3f3f3f3f;
const int mod = 1e9 + 7;

struct Edge{
    int to;
    int next;
    int w;
}edge[maxn*2];
int head[maxn];
int cur[maxn];//當前弧優化陣列
int
n, m, s, t;//點數,邊數,源點,匯點 int dis[maxn];//Bfs深度 int cnt = 0;//邊數 int x; inline void init(){ cnt = 0; memset(head, -1, sizeof head); } inline void Add_Edge(int u, int v, int w){ edge[cnt].next = head[u]; edge[cnt].to = v; edge[cnt].w = w; head[u] = cnt++; } inline bool Bfs(){ for
(int i = 1; i <= n; ++i) dis[i] = -1; dis[s] = 0; queue<int> q; q.push(s); while(!q.empty()){ int u = q.front(); q.pop(); for(int i = head[u]; i != -1; i = edge[i].next){ int v = edge[i].to; if(dis[v] == -1 && edge[i].w){//沒有標記深度並且有殘量
dis[v] = dis[u] + 1; q.push(v); } } } return dis[t] != -1; } inline int dfs(int u, int flow){ if(u == t) return flow; int del = flow; for(int i = cur[u]; i != -1; i = edge[i].next){ cur[u] = edge[i].next;//當前弧優化,下次直接從cur[u]開始增廣,節省時間 int v = edge[i].to; if(dis[v] == dis[u] + 1 && edge[i].w > 0){//深度+1且殘量大於0 int ans = dfs(v, min(del, edge[i].w));//木桶原理 edge[i].w -= ans;//正向弧減增廣流量 edge[i ^ 1].w += ans;//反向弧加增廣流量 del -= ans;//總流量減增廣流量 if(del == 0) break;//總流量為0則不繼續增廣 } } return flow - del;//返回本次增廣的流量 } inline int Dinic(){ int ans = 0; while(Bfs()){ for(int i = 1; i <= n; ++i) cur[i] = head[i]; ans += dfs(s, inf); } return ans; } int main(){ scanf("%d %d %d", &n, &m, &x); s = 1, t = n; init(); for(int i = 1; i <= m; ++i){ int u, v, w; scanf("%d %d %d", &u, &v, &w); Add_Edge(u, v, w); Add_Edge(v, u, 0); } int ans = Dinic(); if (!ans) cout << "Orz Ni Jinan Saint Cow!" << endl; else { int ans1 = ceil(x*1./ans); printf("%d %d\n", ans, ans1); } return 0; }
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ISAP模板

#pragma GCC optimize(2)
#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 10;
//const int maxm = 1e3 * 2 + 10;
const int inf = 0x3f3f3f3f;
const int mod = 1e9 + 7;
int m,n,s,t, x, head[maxn], num_edge;
int cur[maxn],deep[maxn],last[maxn],num[maxn];
//cur當前弧優化; last該點的上一條邊; num桶 用來GAP優化
struct Edge{
    int next,to,dis;
}edge[maxn*2];

void add_edge(int from,int to,int dis)
{
    edge[num_edge].to=to;
    edge[num_edge].dis=dis;
    edge[num_edge].next=head[from];
    head[from]=num_edge++;
}
//bfs僅用於更新deep
void bfs(int t)
{
    queue<int>q;
    for (int i=0; i<=n; i++) cur[i]=head[i];
    for (int i=1; i<=n; i++) deep[i]=n;
    deep[t]=0;
    q.push(t);
    while (!q.empty())
    {
        int now=q.front(); q.pop();
        for (int i=head[now]; i != -1; i=edge[i].next)
        {
            if (deep[edge[i].to]==n && edge[i^1].dis)//i^1是為了找反邊
            {
                deep[edge[i].to] = deep[now]+1;
                q.push(edge[i].to);
            }
        }
    }
}

int add_flow(int s,int t)
{
    int ans=inf,now=t;
    while (now!=s)
    {
        ans=min(ans,edge[last[now]].dis);
        now=edge[last[now]^1].to;
    }
    now=t;
    while (now!=s)
    {
        edge[last[now]].dis-=ans;
        edge[last[now]^1].dis+=ans;
        now=edge[last[now]^1].to;
    }
    return ans;
}
int isap(int s,int t)
{
    int now=s;
    int maxflow = 0;
    bfs(t);//搜出一條增廣路
    for (int i=1; i<=n; i++) num[deep[i]]++;
    while (deep[s]<n)
    {
        if (now==t)
        {//如果到達匯點就直接增廣,重新回到源點進行下一輪增廣
            maxflow+=add_flow(s,t);
            now=s;//回到源點
        }
        bool has_find=0;
        for (int i=cur[now]; i!=-1; i=edge[i].next)
        {
            if (deep[now]==deep[edge[i].to]+1 && edge[i].dis)//找到一條增廣路
            {
                has_find=true;
                cur[now]=i;//當前弧優化
                now=edge[i].to;
                last[edge[i].to]=i;
                break;
            }
        }
        if (!has_find)//沒有找到出邊,重新編號
        {
            int minn=n-1;
            for (int i=head[now]; i!=-1; i=edge[i].next)//回頭找路徑
                if (edge[i].dis)
                    minn=min(minn,deep[edge[i].to]);
            if ((--num[deep[now]])==0) break;//GAP優化 出現了斷層
            num[deep[now]=minn+1]++;
            cur[now]=head[now];
            if (now!=s)
                now=edge[last[now]^1].to;
        }
    }
    return maxflow;
}
int main(){
    num_edge = 0;
    memset(head,-1,sizeof(head));
    scanf("%d%d%d",&n,&m,&x);
    for(int i=0;i<m;i++){
            int u,v,cap;
            scanf("%d%d%d",&u,&v,&cap);
            add_edge(u,v,cap);
            add_edge(v,u,0);
    }
    s = 1, t = n;
    int ans = isap(s,t);
    if (!ans) cout << "Orz Ni Jinan Saint Cow!" << endl;
    else {
        int ans2 = ceil(x*1./ans);
        printf("%d %d\n", ans, ans2);
    }

    return 0;
}
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