HDU 4424 Conquer a New Region and query set, hdu4424

HDU 4424 Conquer a New Region and query set, hdu4424

Given n points and n-1 edges, the maximum carrying capacity between a and B is the minimum carrying capacity between a and B. Take a certain point as the center, and calculate the maximum value of the sum of carrying capacity.

Since the carrying capacity between a and B is the minimum value of the carrying capacity between them, the carrying capacity between two points is first sorted from large to small. Each merge has two sets, A and B. The cost between them is the current minimum. If B is merged to A, the total CARRYING CAPACITY OF A is the total carrying capacity before A plus, the load between two equal parts (cost [A] = cost [A] + num [B] * cost.

#include <iostream>#include <cstdio>#include <cmath>#include <cstring>#include <algorithm>using namespace std;typedef long long ll;const int inf=1000000000;const int maxn=200005;int f[maxn];ll num[maxn],cost[maxn];struct Branch{    int a;    int b;    ll cost;}bra[maxn];bool cmp(Branch a,Branch b){    return a.cost>b.cost;}int Find(int x){    if(x!=f[x])        f[x]=Find(f[x]);    return f[x];}ll Function(int n){    for(int i=0;i<n-1;i++)    {        int a=Find(bra[i].a);        int b=Find(bra[i].b);        if(cost[a]+num[b]*bra[i].cost>=cost[b]+num[a]*bra[i].cost)        {            f[b]=a;            cost[a]+=num[b]*bra[i].cost;            num[a]+=num[b];        }        else        {            f[a]=b;            cost[b]+=num[a]*bra[i].cost;            num[b]+=num[a];        }    }    return cost[Find(1)];}int main(){    //freopen("in.txt","r",stdin);    int n;    while(scanf("%d",&n)!=EOF)    {        for(int i=0;i<=n;i++)        {            f[i]=i;            num[i]=1;        }        memset(cost,0,sizeof(cost));        for(int i=0;i<n-1;i++)            scanf("%d%d%I64d",&bra[i].a,&bra[i].b,&bra[i].cost);        sort(bra,bra+n-1,cmp);        printf("%I64d\n",Function(n));    }    return 0;}