[BZOJ2324][ZJOI2011][最小费用最大流]营救皮卡丘

/**************************************************************
    Problem: 2324
    User: gaotianyu1350
    Language: C++
    Result: Accepted
    Time:392 ms
    Memory:7620 kb
****************************************************************/
 
#include <cstdio>
#include <cstring>
#include <cmath>
#include <cstdlib>
#include <queue>
#include <iostream>
using namespace std;
 
#define MAXN 350
#define MAXM 300000
#define INF  0x3f3f3f3f
 
int point[MAXN], next[MAXM], v[MAXM], flow[MAXM], cap[MAXM], w[MAXM];
int lastedge[MAXN], dis[MAXN];
bool check[MAXN];
int tot = -1;
 
int n, m, people;
int map[MAXN][MAXN];
 
inline void init()
{
    memset(map, 0x7f, sizeof(map));
    memset(point, -1, sizeof(point));
    memset(next, -1, sizeof(next));
    tot = -1;
}
 
inline void addedge(int x, int y, int theCap, int theDis)
{
    tot++;
    next[tot] = point[x]; point[x] = tot; 
    v[tot] = y; flow[tot] = 0; cap[tot] = theCap; w[tot] = theDis;
    tot++;
    next[tot] = point[y]; point[y] = tot;
    v[tot] = x; flow[tot] = 0; cap[tot] = 0; w[tot] = - theDis;
}
 
inline int addflow(int s, int t)
{
    int now = t;
    int ans = INF;
    while (now != s)
    {
        int temp = lastedge[now];
        ans = min(ans, cap[temp] - flow[temp]);
        now = v[lastedge[now] ^ 1];
    }
    now = t;
    while (now != s)
    {
        flow[lastedge[now]] += ans;
        flow[lastedge[now] ^ 1] -= ans;
        now = v[lastedge[now] ^ 1];
    }
    return ans;
}
 
bool spfa(int s, int t, int &maxflow, int &mincost)
{
    queue<int> q;
    while (!q.empty()) q.pop();
    memset(dis, 0x7f, sizeof(dis));
    memset(check, 0, sizeof(check));
    dis[s] = 0; check[s] = true; q.push(s);
    while (!q.empty())
    {
        int now = q.front(); q.pop();
        check[now] = false;
        for (int temp = point[now]; temp != -1; temp = next[temp])
            if (flow[temp] < cap[temp] && dis[now] + w[temp] < dis[v[temp]])
            {
                dis[v[temp]] = dis[now] + w[temp];
                lastedge[v[temp]] = temp;
                if (!check[v[temp]])
                    check[v[temp]] = true, q.push(v[temp]);
            }
    }
    if (dis[t] > INF) return false;
    int add = addflow(s, t);
    maxflow += add;
    mincost += add * dis[t];
    return true;
}
 
inline int solve(int s, int t)
{
    int maxflow = 0, mincost = 0;
    while (spfa(s, t, maxflow, mincost));
    /*{
        int tiaoshi = 1;
        tiaoshi++;
    }*/
    //printf("mflow :%d\n", maxflow);
    return mincost;
}
 
inline void build(int start, int end)
{
    addedge(start, 0, people, 0);
    for (int i = 1; i <= n; i++)
    {
        addedge(i, end, 1, 0);
        addedge(start, i + n, 1, 0);
        //addedge(i, i + n, INF, 0);
    }
    for (int k = 0; k <= n; k++)
    for (int i = 0; i <= n; i++)
    for (int j = 0; j <= n; j++)
        if (i != j)
        {
            if (map[i][k] < INF && map[k][j] < INF)
                map[i][j] = min(map[i][j], map[i][k] + map[k][j]);
            if (k == j && i < j && map[i][j] < INF)
                addedge(i == 0 ? 0 : i + n, j, INF, map[i][j]);       
        }   
}
 
int main()
{
    //freopen("input.txt", "r", stdin);
    init();
    scanf("%d%d%d", &n, &m, &people);
    for (int i = 1; i <= m; i++)
    {
        int x, y, z;
        scanf("%d%d%d", &x, &y, &z);
        if (z < map[x][y])
            map[x][y] = map[y][x] = z;
    }
    build(2 * n + 1, 2 * n + 2);
    printf("%d\n", solve(2 * n + 1, 2 * n + 2));
}