【HDU4366】【DFS序+分块】Successor

  1 #include <iostream>
  2 #include <cstdio>
  3 #include <algorithm>
  4 #include <cstring>
  5 #include <vector>
  6 #include <utility>
  7 #include <iomanip>
  8 #include <string>
  9 #include <cmath>
 10 #include <queue>
 11 #include <assert.h>
 12 #include <map>
 13 
 14 const int N = 55555 + 10;
 15 const int SIZE = 250;//块状链表的大小 
 16 const int M = 50000 + 5;
 17 using namespace std;
 18 typedef long long ll;
 19 struct DATA {
 20     int a, b;
 21 }data[N], list[N], Sort[N];
 22 bool operator < (DATA a,DATA b) {
 23     return a.b < b.b;
 24 }
 25 map<int,int> Map;
 26 vector<int>G[N];
 27 int pos[N], tot, Max[N];
 28 int size[N], n, q;
 29 
 30 //二分搜索
 31 int search(int l, int r, int val){
 32     if (Sort[r].b <= val) return -1;
 33     if (Sort[l].b > val) return Max[l];
 34     while (l + 1 < r) {
 35         int mid = (l + r) >> 1;
 36         if (Sort[mid].b > val) r = mid; 
 37         else l = mid;
 38     }
 39     return Max[r];
 40 }
 41 int dfs(int u){
 42     pos[u] = tot;
 43     list[tot] = Sort[tot] = data[u];
 44     tot++;//tot为时间序 
 45     int cnt = 1;
 46     for (int i = 0; i < G[u].size(); i++){
 47         int v = G[u][i];
 48         cnt += dfs(v);
 49     }
 50     return size[pos[u]] = cnt;
 51 }
 52 
 53 void prepare(){
 54      memset(data, -1, sizeof(data));
 55      memset(Sort, -1, sizeof(Sort));
 56      memset(list, -1, sizeof(list));
 57      memset(Max, 0, sizeof(Max));
 58      memset(size, 0, sizeof(size));
 59      memset(pos, 0, sizeof(pos));
 60      scanf("%d%d", &n, &q);
 61      for (int i = 0; i < n; i++) G[i].clear();//初始化邻接表 
 62      Map.clear();
 63      Map[-1] = -1;
 64 }
 65 void init(){
 66      for (int i = 1; i < n; i++){
 67          int fa, x, y;
 68          scanf("%d%d%d", &fa, &x, &y);
 69          G[fa].push_back(i);
 70          data[i].a = x;
 71          data[i].b = y;
 72          Map[x] = i;
 73      }
 74      tot = 0;
 75      dfs(0);//构图 
 76 }
 77 void dp(){
 78       //预处理出每一个块内的值，好二分 
 79       for (int i = 0; i < n; i += SIZE){
 80           int j = i + SIZE;
 81           if (j > n) break;
 82           sort(Sort + i, Sort + j);
 83           Max[j - 1] = Sort[j - 1].a;
 84           //块内地推 
 85           for (int k = j - 2; k >= i;k--) Max[k] = max(Max[k + 1], Sort[k].a);
 86       } 
 87 }
 88 void query(int l, int r, int val){
 89      int ans = -1;
 90      for (int i = l; i <= r;){
 91          if (i % SIZE == 0 && i + SIZE - 1 <= r){
 92             int tmp = search(i, i + SIZE - 1, val);
 93             ans = max(ans, tmp);
 94             i += SIZE;
 95          }else{//暴力 
 96             if (list[i].b > val && list[i].a > ans) ans = list[i].a;
 97             i++;
 98          }
 99      }
100      //printf("%d\n", ans);
101      printf("%d\n", Map[ans]);
102 }
103 void work(){
104      for (int i = 1; i <= q; i++){
105          int x, val;
106          scanf("%d", &x);
107          val = data[x].b;
108          x = pos[x];
109          int y = x + size[x] - 1;//size用来存子树的大小
110          //printf("*%d*\n", y);
111          query(x, y, val);
112      } 
113 }
114 
115 int main(){
116     int T;
117     #ifdef LOCAL
118     freopen("data.txt", "r", stdin);
119     freopen("out.txt", "w", stdout);
120     #endif
121     scanf("%d", &T);
122     while (T--){
123           prepare();//初始化
124           init(); 
125           dp();
126           work(); 
127     }
128     return 0;
129 }