[HIHO1299]打折机票（线段树）

 1 #include <algorithm>
 2 #include <iostream>
 3 #include <iomanip>
 4 #include <cstring>
 5 #include <climits>
 6 #include <complex>
 7 #include <fstream>
 8 #include <cassert>
 9 #include <cstdio>
10 #include <bitset>
11 #include <vector>
12 #include <deque>
13 #include <queue>
14 #include <stack>
15 #include <ctime>
16 #include <set>
17 #include <map>
18 #include <cmath>
19 
20 using namespace std;
21 
22 //kirai²»ÊÇɳ²è£¬²»»áÍü¼ÇÐÞ¸Ämaxn
23 #define lson l, m, rt << 1
24 #define rson m + 1, r, rt << 1 | 1
25 typedef long long ll;
26 typedef struct Node {
27     int t, v;
28 }Node;
29 const int maxn = 100010;
30 int n, m;
31 int sum[maxn<<2];
32 
33 void pushUP(int rt) {
34     //modify
35     sum[rt] = max(sum[rt<<1], sum[rt<<1|1]);
36 }
37 
38 void build(int l, int r, int rt) {
39     if(l == r) {
40         sum[rt] = -1;
41         return;
42     }
43     int m = (l + r) >> 1;
44     build(lson);
45     build(rson);
46     pushUP(rt);
47 }
48 
49 void update(int p, int add, int l, int r, int rt) {
50     if(l == r) {
51         sum[rt] = max(sum[rt], add);
52         return;
53     }
54     int m = (l + r) >> 1;
55     if(p <= m) {
56         update(p, add, lson);
57     }
58     else {
59         update(p, add, rson);
60     }
61     pushUP(rt);
62 }
63 
64 int query(int L, int R, int l, int r, int rt) {
65     if(L <= l && r <= R) {
66         return sum[rt];
67     }
68     int m = (l + r) >> 1;
69     int ret = 0;
70     if(L <= m) {
71         //modify
72         ret = max(ret, query(L, R, lson));
73     }
74     if(R > m) {
75         //modify
76         ret = max(ret, query(L, R, rson));
77     }
78     return ret;
79 }
80 
81 int main() {
82     // freopen("in", "r", stdin);
83     while(~scanf("%d%d", &n, &m)) {
84         int t, v;
85         build(1, n, 1);
86         for(int i = 0; i < n; i++) {
87             scanf("%d%d", &t, &v);
88             update(t, v, 1, n, 1);
89         }
90         int a, b;
91         while(m--) {
92             scanf("%d%d", &a, &b);
93             int ans = query(a, b, 1, n, 1);
94             if(ans <= 0) printf("None\n");
95             else printf("%d\n", ans);
96         }
97     }
98     return 0;
99 }