POJ-1273-Drainage Ditches（最大流）dinic实现 后续模板待补充

Sample Input

5 41 2 401 4 202 4 202 3 303 4 10

Sample Output

50

#include <iostream>#include <stdio.h>#include <string.h>#include <stack>#include <queue>#include <map>#include <set>#include <vector>#include <math.h>#include <bitset>#include <algorithm>#include <climits>using namespace std;#define MAXN 1005#define INF 0x3f3f3f3f/*int maze[MAXN][MAXN];int gap[MAXN],dis[MAXN],pre[MAXN],cur[MAXN];int sap(int start, int end, int nodenum){    memset(cur,0,sizeof(cur));    memset(dis,0,sizeof(dis));    memset(gap,0,sizeof(gap));    int u=pre[start]=start, maxflow=0,aug=-1;    gap[0]=nodenum;    while(dis[start]<nodenum)    {loop:        for(int v=cur[u]; v<nodenum; ++v)            if(maze[u][v]&&dis[u]==dis[v]+1)            {                if(aug==-1 ||aug>maze[u][v])aug=maze[u][v];                pre[v]=u;                u=cur[u]=v;                if(v==end)                {                    maxflow+=aug;                    for(u=pre[u]; v!=start; v=u,u=pre[u])                    {                        maze[u][v]-=aug;                        maze[v][u]+=aug;                    }                    aug=-1;                }                goto loop;            }        int mindis=nodenum-1;        for(int v=0; v<nodenum; ++v)            if(maze[u][v]&&mindis>dis[v])            {                cur[u]=v;                mindis=dis[v];            }        if((--gap[dis[u]])==0)break;        gap[ dis[u]=mindis+1 ]++;        u=pre[u];    }    return maxflow;}*/int head[MAXN],index;struct node{    int v,next,val;}eage[MAXN];void add_eage(int a,int b,int val){    eage[index].v=b;    eage[index].val=val;    eage[index].next=head[a];    head[a]=index++;}int deep[MAXN];bool bfs(int start,int end){    int i,j;    memset(deep,0,sizeof(deep));    deep[start]=1;    queue<int> q;    while(!q.empty())q.pop();    q.push(start);    while(!q.empty())    {        int u=q.front();        q.pop();        if(u==end)return 1;        for(i=head[u]; i!=-1; i=eage[i].next)        {            int v=eage[i].v;            if(!deep[v] && eage[i].val>0)            {                deep[v]=deep[u]+1;                q.push(v);            }        }    }    return 0;}int DFS(int start, int max_, int end){    if(start==end)return max_;    int i,ans=0,f;    for(i=head[start]; i!=-1 && ans<max_; i=eage[i].next)    {        int v=eage[i].v;        if(deep[start]+1==deep[v] && eage[i].val>0)        {            f=DFS(v,min(max_-ans,eage[i].val),end);            eage[i].val-=f;            eage[i^1].val+=f;            ans+=f;            if(ans==max_)return ans;        }    }    //if(!ans)deep[start]=-2;    return ans;}int DINIC(int start,int end){    int ans=0,t;    while(bfs(start,end))        while(t=DFS(start,INF,end))        ans+=t;    return ans;}int main(){    int m,n,a,b,v;    while(~scanf("%d%d",&m,&n))    {        index=0;        memset(head,-1,sizeof(head));        for(int i=0; i<m; ++i)        {            scanf("%d%d%d",&a,&b,&v);            add_eage(a,b,v);            add_eage(b,a,0);        }        cout<<DINIC(1,n)<<endl;    }    return 0;}