poj 1987 节点距离小于等于K（树DP）

这题和poj 1741是一模一样的

但是1741能AC的代码，在这里却是TLE，暂时没看出哪里出现了问题。。

AC代码：

#include <iostream>
#include <string>
#include <cstring>
#include <cstdlib>
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <stack>
#include <queue>
#include <cctype>
#include <vector>
#include <iterator>
#include <set>
#include <map>
#include <sstream>
using namespace std;

#define mem(a,b) memset(a,b,sizeof(a))
#define pf printf
#define sf scanf
#define spf sprintf
#define pb push_back
#define debug printf("!
")
#define MAXN 40000+5
#define MAX(a,b) a>b?a:b
#define blank pf("
")
#define LL long long
#define ALL(x) x.begin(),x.end()
#define INS(x) inserter(x,x.begin())
#define pqueue priority_queue
#define INF 0x3f3f3f3f

#define ls (rt<<1)
#define rs (rt<<1|1)

int n,m,k;

int ans,root,tot,ptr = 1,K,son[MAXN],head[MAXN],f[MAXN],dist[MAXN],d[MAXN],sum,vis[MAXN];

struct node{int y,next,v;}tree[MAXN<<2];

void add(int u,int v,int w) {tree[ptr].y=v;tree[ptr].v=w;tree[ptr].next=head[u];head[u]=ptr++;}

void getroot(int x,int fa)
{
    son[x] = 1;
    f[x] = 0;
    for(int i=head[x];i!=-1;i=tree[i].next)
    {
        int y = tree[i].y;
        if(y == fa || vis[y]) continue;
        getroot(y,x);
        son[x] += son[y];
        f[x] = max(f[x] , son[y]);
    }
    f[x] = max(f[x] , sum - son[x]);
    if(f[x] < f[root]) root = x;
}

void getdis(int x,int fa)
{
    if(d[x] <= K) dist[tot++]=d[x];
    for(int i=head[x];i!=-1;i=tree[i].next)
    {
        int y = tree[i].y;
        if(y == fa || vis[y]) continue;
        d[y] = d[x] + tree[i].v;
        getdis(y,x);
    }
}

int cal(int x,int now)
{
    d[x]=now;
    tot = 0;
    getdis(x,0);
    sort(dist,dist+tot);
    int all = 0,left=0,right = tot-1;
    while(left<right)
    {
        if(dist[left]+dist[right] <= K) {all+=right-left;left++;}
        else right--;
    }
    return all;
}
void solve(int x)
{
    ans+=cal(x,0);
    vis[x] = 1;
    for(int i=head[x];i!=-1;i=tree[i].next)
    {
        int y = tree[i].y;
        if(vis[y]) continue;
        ans-=cal(y,tree[i].v);
        sum = son[y];
        root = 0;
        getroot(y,root);
        solve(root);
    }
}
void init()
{
    mem(head,-1);
    ptr = 1;
    ans = root = 0;
    mem(vis,0);
    sum=n;
    f[0]=INF;
}

int main()
{
    while(~sf("%d%d",&n,&m))
    {
        init();
        for(int i=1;i<n;i++)
        {
            int x,y,z;char ch[2];
            sf("%d%d%d%s",&x,&y,&z,ch);
            add(x,y,z);
            add(y,x,z);
        }
        sf("%d",&K);
        getroot(1,0);
        solve(root);
        pf("%d
",ans);
    }

}

1741可AC，这题TLE

#include <iostream>
#include <string>
#include <cstring>
#include <cstdlib>
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <stack>
#include <queue>
#include <cctype>
#include <vector>
#include <iterator>
#include <set>
#include <map>
#include <sstream>
using namespace std;

#define mem(a,b) memset(a,b,sizeof(a))
#define pf printf
#define sf scanf
#define spf sprintf
#define pb push_back
#define debug printf("!
")
#define MAXN 40000+5
#define MAX(a,b) a>b?a:b
#define blank pf("
")
#define LL long long
#define ALL(x) x.begin(),x.end()
#define INS(x) inserter(x,x.begin())
#define pqueue priority_queue
#define INF 0x3f3f3f3f

#define ls (rt<<1)
#define rs (rt<<1|1)

int n,m,k;

int ptr = 1,head[MAXN],vis[MAXN],f[MAXN],d[MAXN];

int ans,tot,rt,sum,son[MAXN],dis[MAXN],mu[MAXN];

struct node
{
    int y,val,next;
}tree[MAXN<<2];

void init()
{
    mem(tree,0);
    mem(head,-1);
    mem(vis,0);
    mem(dis,0);
    ans = 0;
    ptr = 1;
    sum = n;
    f[0] = INF;
}

void add(int fa,int son,int val)
{
    tree[ptr].y = son;
    tree[ptr].val = val;
    tree[ptr].next = head[fa];
    head[fa] = ptr++;
}

void getroot(int root,int fa)
{
    son[root] = 1;
    f[root] = 0;
    for(int i=head[root];i!=-1;i=tree[i].next)
    {
        int y = tree[i].y;
        if(vis[y] || y == fa) continue;
        getroot(y,root);
        son[root] += son[y];
        f[root] = max(son[y],f[root]);
    }
    f[root] = max(f[root],sum-son[root]);
    if(f[root]<f[rt]) rt = root;
}

void getdis(int root,int fa)
{
    if(d[root]<=k) dis[tot++] = d[root];
    for(int i=head[root];i!=-1;i=tree[i].next)
    {
        int y = tree[i].y;
        if(vis[y] || y == fa) continue;
        d[y] = d[root] + tree[i].val;
        getdis(y,root);
    }
}

int getcnt(int root,int now)
{
    d[root] = now;
    tot = 0;
    getdis(root,0);
    sort(dis,dis+tot);
    int left =0,right = tot-1,ans=0;
    while(left<right)
    {
        if(dis[left]+dis[right]<=k)
        {
            ans+= right-left;
            left++;
        }
        else right--;
    }
    return ans;
}

void solve(int root)
{
    //pf("rt%d
",rt);
    ans+=getcnt(root,0);
    vis[root] = 1;
    for(int i=head[root];i!=-1;i=tree[i].next)
    {
        int y = tree[i].y;
        if(vis[y]) continue;
        ans-=getcnt(y,tree[i].val);
        sum = son[y];
        rt = 0;
        getroot(y,rt);
        solve(rt);
    }
}


int main()
{
    int i,j,t,kase=1;
    while(~sf("%d%d",&n,&m),n+m)
    {
        init();
        int x,y,z;
        char ch[2];
        for(i=1;i<n;i++)
        {
            sf("%d%d%d%s",&x,&y,&z,ch);
            add(x,y,z);
            add(y,x,z);
        }
        sf("%d",&k);
        getroot(1,0);
        solve(rt);
        pf("%d
",ans);
    }
    return 0;
}

以及：http://blog.csdn.net/woshi250hua/article/details/7723400

我看起来是一样的，就是不知道TLE的原因。。