线段树。
1 #include <iostream>
2 #include <cstdio>
3 #include <cstring>
4 using namespace std;
5
6 #define mymax(a, b) (a>b) ? a:b
7
8 const int maxn = 200005;
9
10 int nums[maxn<<2];
11
12 void PushUP(int rt) {
13 nums[rt] = mymax(nums[rt<<1], nums[rt<<1|1]);
14 }
15
16 void build(int l, int r, int rt) {
17 if (l == r) {
18 scanf("%d", &nums[rt]);
19 return ;
20 }
21 int mid = (l+r)>>1;
22 build(l, mid, rt<<1);
23 build(mid+1, r, rt<<1|1);
24 PushUP(rt);
25 }
26
27 int query(int ll, int rr, int l, int r, int rt) {
28 if (ll <= l && rr>= r)
29 return nums[rt];
30 int mid = (l+r)>>1;
31 int max = -1, tmp = -1;
32 if (ll <= mid) {
33 max = query(ll, rr, l, mid, rt<<1);
34 }
35 if (rr > mid) {
36 tmp = query(ll, rr, mid+1, r, rt<<1|1);
37 if (tmp > max)
38 max = tmp;
39 }
40 return max;
41 }
42
43 void update(int des, int val, int l, int r, int rt) {
44 if (l == r) {
45 nums[rt] = val;
46 return ;
47 }
48 int mid = (l+r)>>1;
49 if (des <= mid)
50 update(des, val, l, mid, rt<<1);
51 else
52 update(des, val, mid+1, r, rt<<1|1);
53 PushUP(rt);
54 }
55
56 int main() {
57 int n, m;
58 int i, j;
59 char cmd[3];
60
61 while (scanf("%d %d", &n, &m) != EOF) {
62 build(1, n, 1);
63 while (m--) {
64 scanf("%*c%s %d %d", cmd, &i, &j);
65 if (cmd[0] == ‘Q‘)
66 printf("%d\n", query(i,j,1,n,1));
67 else
68 update(i,j,1,n,1);
69 }
70 }
71
72 return 0;
73 }
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时间： 2024-12-23 01:00:15