hdu 4123 rmq与树的直径

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#include <bits/stdc++.h>using namespace std;#define ll long longconst int inf = 0x7f7f7f7f;const int maxn = 5e4 + 10;deque<int> Max, Min;struct node{    int v, w;    node(){}    node(int _v, int _w){        v = _v; w = _w;    }};int LOG[2*maxn]; int dp1[20][2*maxn]; int dp2[20][2*maxn];int num[maxn];void rmq_init(int n) {     int i,j;     for(j=1;j<=n;j++)   {         dp1[0][j]=num[j];         dp2[0][j]=num[j];     }     for(j=1;j<=LOG[n];j++)   {         int limit=n+1-(1<<j);         for(i=1;i<=limit;i++)    {             int x=i+(1<<j>>1);             dp1[j][i]=min(dp1[j-1][x],dp1[j-1][i]);             dp2[j][i]=max(dp2[j-1][x],dp2[j-1][i]);         }     } } int rmq_min(int l,int r) {     int m=LOG[r-l+1];     return min(dp1[m][l],dp1[m][r-(1<<m)+1]); } int rmq_max(int l,int r) {     int m=LOG[r-l+1];     return max(dp2[m][l],dp2[m][r-(1<<m)+1]); } int n, m, x, y, z, q;int vis[maxn];vector<node>aa[maxn];int disf[maxn], diss[maxn], a[maxn];void bfs(int s, int &ss, int dist[]){    memset(dist, inf, sizeof( dist ));    memset(vis, 0 ,sizeof( vis ));    queue<int> q;    int maxx = 0;    q.push(s); vis[s] = 1; dist[s] = 0;    while(!q.empty() ){        int now = q.front(); q.pop();        for(int i = 0 ; i < aa[now].size(); i++){            int v = aa[now][i].v; int w = aa[now][i].w;            if(vis[v]) continue;            vis[v] = 1;            dist[v] = dist[now] + w;            if(dist[v] > maxx){                maxx = dist[v]; ss = v;            }            q.push(v);        }    }}int main(){    LOG[0] = -1;     for(int i = 1;i < 2 * maxn; i++) LOG[i] = LOG[i>>1] + 1;    while(scanf("%d%d", &n, &q) , n || q){        for(int i = 1 ; i <= n ; i ++) aa[i].clear();        for(int i = 1 ;i < n ; i ++){            scanf("%d%d%d", &x, &y, &z);            aa[x].push_back(node(y, z));            aa[y].push_back(node(x, z));        }        int ss, tt;    //  puts("nima");        bfs(1, ss, disf);//cout<<" ss = "<<ss<<endl;        bfs(ss, tt, disf);//cout<<" ff = "<<tt<<endl;        bfs(tt, ss, diss);    //  puts("nimab");        for(int i = 1; i <= n; i++)     num[i] = max(disf[i], diss[i]);    //  for(int i = 1; i <= n; i++)     cout << " i = " <<i<<" "<< disf[i] <<endl;    //  while( !Max.empty() ) Max.pop_back() ;      //  while( !Min.empty() ) Min.pop_back() ;        int i, j; int ans;        //puts("nimabi ");        rmq_init(n);         while(q--)    {             scanf("%d",&m);             int ans = 0;             int l = 1,r = 1, mx, mi;             while(r <= n)    {                 mx = rmq_max(l, r);                 mi = rmq_min(l, r);                 if(mx - mi <= m )    {                     ans = max(ans, r - l + 1);                     r++;                 }                 else l++;             }             printf("%d\n",ans);        }    }}
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