链接：http://acm.hdu.edu.cn/showproblem.php?pid=5889
解法：http://blog.csdn.net/u013532224/article/details/46992973 然后改改模版
#include <iostream>
#include <cstring>
#include <cstdio>
#include <vector>
#include <queue>
#include <string.h>
using namespace std;
const int MAXN = 2200;//点数的最大值
const int MAXM = 800000;//边数的最大值
const int INF2 = 2000000000;
struct Edge1
{
int to,next,cap,flow;
}edge[MAXM];//注意是MAXM
int tol;
int head[MAXN];
int gap[MAXN],dep[MAXN],cur[MAXN];
void init()
{
tol = 0;
memset(head,-1,sizeof (head));
}
void add (int u,int v,int w,int rw = 0)//网络流要有反向弧
{
edge[tol].to = v; edge[tol].cap = w; edge[tol].flow = 0;
edge[tol].next = head[u]; head[u] = tol++;
edge[tol].to = u; edge[tol].cap = rw; edge[tol].flow = 0;
edge[tol].next = head[v]; head[v] = tol++;
}
int Q[MAXN];
void BFS(int start,int end)
{
memset(dep,-1,sizeof(dep));
memset(gap,0,sizeof(gap));
gap[0] = 1;
int front = 0, rear = 0;
dep[end] = 0;
Q[rear++] = end;
while(front != rear)
{
int u = Q[front++];
for(int i = head[u]; i != -1; i = edge[i].next)
{
int v = edge[i]. to;
if(dep[v] != -1)continue;
Q[rear++] = v;
dep[v] = dep[u] + 1;
gap[dep[v]]++;
}
}
}
int S[MAXN];
int sap(int start,int end, int N)//有几个点
{
BFS(start,end);
memcpy(cur,head,sizeof(head));
int top = 0;
int u = start;
int ans = 0;
int i;
while(dep[start] < N)
{
if(u == end)
{
int Min = INF2;
int inser;
for( i = 0;i < top;i++)
{
if(Min > edge[S[i]].cap - edge[S[i]].flow)
{
Min = edge[S[i]].cap - edge[S[i]].flow;
inser = i;
}
}
for( i = 0;i < top;i++)
{
edge[S[i]]. flow += Min;
edge[S[i]^1].flow -= Min;
}
ans += Min;
top = inser;
u = edge[S[top]^1].to;
continue;
}
bool flag = false;
int v;
for( i = cur[u]; i != -1; i = edge[i]. next)
{
v = edge[i]. to;
if(edge[i].cap - edge[i].flow && dep[v]+1 == dep[u])
{
flag = true;
cur[u] = i;
break;
}
}
if(flag)
{
S[top++] = cur[u];
u = v;
continue;
}
int Min = N;
for( i = head[u]; i != -1; i = edge[i].next)
{
if(edge[i].cap - edge[i].flow && dep[edge[i].to] < Min)
{
Min = dep[edge[i].to];
cur[u] = i;
}
}
gap[dep[u]]--;
if(!gap[dep[u]]) return ans;
dep[u] = Min + 1;
gap[dep[u]]++;
if(u != start)u = edge[S[--top]^1].to;
}
return ans;
}
#define typec int
typec INF=0x3f3f3f3f;//防止后面溢出，这个不能太大
bool vis[MAXN];
int pre[MAXN];
void Dijkstra(typec cost[][MAXN],typec lowcost[],int n,int beg)
{
for(int i=0;i<n;i++)
{
lowcost[i]=INF;
vis[i]=false;
pre[i]=-1;
}
lowcost[beg]=0;
for(int j=0;j<n;j++)
{
int k=-1;
int Min=INF;
for(int i=0;i<n;i++)
if(!vis[i]&&lowcost[i]<Min)
{
Min=lowcost[i];
k=i;
}
if(k==-1)break;
vis[k]=true;
for(int i=0;i<n;i++)
if(!vis[i]&&lowcost[k]+cost[k][i]<lowcost[i])
{
lowcost[i]=lowcost[k]+cost[k][i];
pre[i]=k;
}
}
}
int cost2[MAXN][MAXN];
int dist2[MAXN];
int cost[MAXN][MAXN];
int num[MAXN][MAXN];
int has[MAXN];
int dist[MAXN];
int main()
{
int T;
cin>>T;
while(T--)
{
int n,m;
scanf("%d%d",&n,&m);
{
init();
memset(cost,INF,sizeof cost);
memset(num,0,sizeof num);
for(int i=0;i<n;i++)
cost[i][i]=0;
for(int i=1;i<=m;i++)//双向 有重边
{
int u,v,w;
scanf("%d%d%d",&u,&v,&w);
u--;
v--;
if(cost[u][v]>w)
{
cost[u][v]=1;
cost[v][u]=1;
}
num[u][v]=w;
num[v][u]=w;
}
Dijkstra(cost,dist,n,0);// wuxiangda bulian
memset(cost2,INF,sizeof cost2);
for(int i=0;i<n;i++)
cost2[i][i]=0;
for(int i=0;i<n;i++)
{
for(int j=0;j<n;j++)
{
if(i!=j)
if(dist[i]-dist[j]==cost[i][j])
{
cost2[j][i]=1;
add(j,i,num[i][j]);
}
}
}
Dijkstra(cost2,dist2,n,0);
printf("%d
",sap(0,n-1,n));
}
}
return 0;
}