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【hdu4366】dfs序线段树
1 #include <bits/stdc++.h> 2 #define ll long long 3 #define lson l, m, rt<<1 4 #define rson m+1, r, rt<<1|1 5 using namespace std; 6 const int N = 5e4+5; 7 8 vector<int> ve[N]; 9 int b[N], c[N], tot; 10 int l[N], r[N], ans[N]; 11 void dfs(int fa, int x){ 12 tot++; 13 l[x] = tot; 14 for(int i = 0; i < ve[x].size(); i++){ 15 int y = ve[x][i]; 16 if(y == fa) continue ; 17 dfs(x, y); 18 } 19 r[x] = tot; 20 } 21 22 struct Node{ 23 int b, pos; 24 Node(){} 25 Node(int b, int pos): b(b), pos(pos){} 26 bool operator <(const Node& a) const{ 27 return b < a.b; 28 } 29 }; 30 Node T[N<<2]; 31 32 void pushup(int rt){ 33 T[rt] = max(T[rt<<1], T[rt<<1|1]); 34 } 35 void build(int l, int r, int rt){ 36 T[rt].b = T[rt].pos = -1; 37 if(l == r) return ; 38 int m = l+r >> 1; 39 build(lson); 40 build(rson); 41 } 42 void update(int pos, Node x, int l, int r, int rt){ 43 if(pos == l&&r == pos){ 44 T[rt] = x; 45 return ; 46 } 47 int m = l+r >> 1; 48 if(pos <= m) update(pos, x, lson); 49 else update(pos, x, rson); 50 pushup(rt); 51 } 52 Node query(int L, int R, int l, int r, int rt){ 53 if(L <= l&&r <= R) 54 return T[rt]; 55 int m = l+r >> 1; 56 Node ret = Node(-1, -1); 57 if(L <= m) ret = max(ret, query(L, R, lson)); 58 if(R > m) ret = max(ret, query(L, R, rson)); 59 return ret; 60 } 61 62 struct p{ 63 int b, c, id, kth; 64 p(){} 65 p(int b, int c, int id, int kth):b(b), c(c), id(id), kth(kth){} 66 bool operator < (const p& a) const{ 67 return c != a.c? c > a.c: kth < a.kth; 68 } 69 }; 70 p pp[N]; 71 72 int main(){ 73 int t; scanf("%d", &t); 74 while(t--){ 75 int n, m, x; 76 scanf("%d%d", &n, &m); 77 for(int i = 0; i < n; i++) ve[i].clear(); 78 b[0] = c[0] = -1; 79 for(int i = 1; i < n; i++){ 80 scanf("%d%d%d", &x, b+i, c+i); 81 ve[x].push_back(i); 82 } 83 84 tot = 0; 85 dfs(-1, 0); 86 for(int i = 0; i < n; i++) 87 pp[i] = p(b[i], c[i], i, l[i]); 88 sort(pp+1, pp+n); 89 build(1, n, 1); 90 for(int i = 1; i < n; i++){ 91 int j = pp[i].id; 92 int L = l[j]+1, R = r[j]; 93 if(L > R) ans[j] = -1; 94 else 95 ans[j] = query(L, R, 1, tot, 1).pos; 96 update(l[j], Node(pp[i].b, pp[i].id), 1, tot, 1); 97 } 98 while(m--){ 99 scanf("%d", &x); 100 printf("%d\n", ans[x]); 101 } 102 } 103 return 0; 104 }
【hdu4366】dfs序线段树
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