HDU3549 Flow Problem(ford-fulkerson算法)

Flow ProblemTime Limit: 5000/5000 MS (Java/Others)    Memory Limit: 65535/32768 K (Java/Others)Total Submission(s): 13984    Accepted Submission(s): 6683Problem DescriptionNetwork flow is a well-known difficult problem for ACMers. Given a graph, your task is to find out the maximum flow for the weighted directed graph.InputThe first line of input contains an integer T, denoting the number of test cases.For each test case, the first line contains two integers N and M, denoting the number of vertexes and edges in the graph. (2 <= N <= 15, 0 <= M <= 1000)Next M lines, each line contains three integers X, Y and C, there is an edge from X to Y and the capacity of it is C. (1 <= X, Y <= N, 1 <= C <= 1000)OutputFor each test cases, you should output the maximum flow from source 1 to sink N.Sample Input23 21 2 12 3 13 31 2 12 3 11 3 1Sample OutputCase 1: 1Case 2: 2AuthorHyperHexagon

第一次接触，最大流问题，其实暑假训练的时候有提及过，之前比赛也接触过费用流的题目，不过不会做。先基础入门。12月1号,生命里最美好的一天，定个小目标，加油。最大流，直接ford-fulkerson,记得c清空vector，然后就可以了。

#include<iostream>#include<cstring>#include<cstdlib>#include<algorithm>#include<cctype>#include<cmath>#include<ctime>#include<string>#include<stack>#include<deque>#include<queue>#include<list>#include<set>#include<map>#include<cstdio>#include<limits.h>#define MOD 1000000007#define fir first#define sec second#define fin freopen("/home/ostreambaba/文档/input.txt", "r", stdin)#define fout freopen("/home/ostreambaba/文档/output.txt", "w", stdout)#define mes(x, m) memset(x, m, sizeof(x))#define Pii pair<int, int>#define Pll pair<ll, ll>#define INF 1e9+7#define inf 0x3f3f3f3f#define Pi 4.0*atan(1.0)#define lowbit(x) (x&(-x))#define lson l,m,rt<<1#define rson m+1,r,rt<<1|1typedef long long ll;typedef unsigned long long ull;const double eps = 1e-12;const int maxn = 16;using namespace std;inline int read(){    int x(0),f(1);    char ch=getchar();    while (ch<'0'||ch>'9') {if (ch=='-') f=-1;ch=getchar();}    while (ch>='0'&&ch<='9') x=x*10+ch-'0',ch=getchar();    return x*f;}struct edge{    int to,cap,rev;};vector<edge> G[maxn];bool used[maxn],f;void addEdge(int from,int to,int cap){    G[from].push_back({to,cap,G[to].size()});    G[to].push_back({from,0,G[from].size()-1});}int dfs(int v,int t,int f){    if(v==t){        return f;    }    used[v]=true;    for(int i=0;i<G[v].size();++i){        edge &e=G[v][i];        if(!used[e.to]&&e.cap>0){            int d=dfs(e.to,t,min(f,e.cap));            if(d>0){                e.cap-=d;                G[e.to][e.rev].cap+=d;                return d;            }        }    }    return 0;}int maxFlow(int s,int t){    int flow=0;    for(;;){        mes(used,false);        int f=dfs(s,t,INF);        if(0==f){            return flow;        }        flow+=f;    }}int main(){   // fin;    int t,n,m,a,b,c;    int cnt=0;    t=read();    while(t--){        cout<<"Case "<<++cnt<<": ";        for(int i=0;i<=n;++i){            G[i].clear();        }        n=read(),m=read();        while(m--){            a=read(),b=read(),c=read();            addEdge(a,b,c);        }        cout<<maxFlow(1,n)<<endl;    }    return 0;}