HDU4417 Super Mario (主席树)
主席树另一模板。
查询的是[L,R]中<=h的个数。
1 #include <bits/stdc++.h> 2 using namespace std; 3 #define lc tr[i].ch[0] 4 #define rc tr[i].ch[1] 5 #define Lc tr[j].ch[0] 6 #define Rc tr[j].ch[1] 7 #define mid ((l + r) >> 1) 8 const int N = 1e5 + 10; 9 int n, m, a[N], b[N]; 10 int cnt, rt[N]; 11 struct node { 12 int num, ch[2]; 13 }tr[N * 20]; 14 void update(int &i, int j, int l, int r, int k) { 15 i = ++ cnt; 16 tr[i] = tr[j]; 17 tr[i].num ++; 18 if (l == r) return ; 19 if (k <= mid) update(lc, Lc, l, mid, k); 20 else update(rc, Rc, mid + 1, r, k); 21 } 22 int query(int i, int j, int l, int r, int k) { 23 if (l == r) return tr[j].num - tr[i].num; 24 int ans = 0; 25 if (k <= mid) ans += query(lc, Lc, l, mid, k); 26 else { 27 ans += tr[Lc].num - tr[lc].num; 28 ans += query(rc, Rc, mid + 1, r, k); 29 } 30 return ans; 31 } 32 int main() { 33 scanf("%d %d", &n, &m); 34 for (int i = 1; i <= n; i ++) { 35 scanf("%d", &a[i]); 36 b[i] = a[i]; 37 } 38 sort(b + 1, b + n + 1); 39 int tot = unique(b + 1, b + n + 1) - b - 1; 40 cnt = 0, rt[0] = 0; 41 for (int i = 1; i <= n; i ++) 42 update(rt[i], rt[i - 1], 1, tot, lower_bound(b + 1, b + tot + 1, a[i]) - b); 43 int l, r, h; 44 while (m --) { 45 scanf("%d %d %d", &l, &r, &h); 46 l ++, r ++; 47 int k = upper_bound(b + 1, b + tot + 1, h) - b - 1;//!!!!! 48 if (k) printf("%d\n", query(rt[l - 1], rt[r], 1, tot, k)); 49 else printf("0\n");//有可能h<所有a[i] 此时k = 0 50 } 51 return 0; 52 }
