思路：更新区间，结构体内保存最大值
1 #include<stdio.h>
2 #include<string>
3 #include<iostream>
4 using namespace std;
5 const int MAXN = 5e4+5;
6 int a[MAXN];
7 struct node
8 {
9 int L,R,sum,la;
10 }tree[MAXN<<2];
11 //建树
12 void Build(int L,int R,int step)
13 {
14 tree[step].L=L;tree[step].R=R;
15 if(L==R)
16 {
17 tree[step].sum=a[L];return;
18 }
19 int mid=(L+R)>>1;
20 Build(L,mid,step<<1);
21 Build(mid+1,R,step<<1|1);
22 tree[step].sum=tree[step<<1].sum+tree[step<<1|1].sum;
23 }
24 //单点查询
25 int Query(int P,int step)
26 {
27 if(tree[step].L==tree[step].R)return tree[step].sum;
28 int mid=(tree[step].L+tree[step].R)>>1;
29 int ans;
30 if(P<=mid)ans=Query(P,step<<1);
31 else Query(P,step<<1|1);
32 return ans;
33 }
34 //单点修改
35 void Add(int P,int val,int step)
36 {
37 if(tree[step].L==tree[step].R)
38 {
39 tree[step].sum+=val;return ;
40 }
41 int mid=(tree[step].L+tree[step].R)>>1;
42 if(P<=mid)Add(P,val,step<<1);
43 else Add(P,val,step<<1|1);
44 tree[step].sum=tree[step<<1].sum+tree[step<<1|1].sum;
45 }
46 //区间查询
47 int Ask(int L,int R,int step)
48 {
49 if(tree[step].L==L&&tree[step].R==R)return tree[step].sum;
50 int mid=(tree[step].L+tree[step].R)>>1;
51 if(R<=mid)return Ask(L,R,step<<1);
52 if(L>mid)return Ask(L,R,step<<1|1);
53 else return Ask(L,mid,step<<1)+Ask(mid+1,R,step<<1|1);
54 }
55 int main()
56 {
57 int T,K=1;
58 scanf("%d",&T);
59 while(T--)
60 {
61 int N;
62 scanf("%d",&N);
63 printf("Case %d:\n",K++);
64 for(int i=1;i<=N;++i)scanf("%d",&a[i]);
65 Build(1,N,1);
66 string s;
67 while(cin>>s)
68 {
69 if(s[0]=='E')break;
70 if(s[0]=='Q')
71 {
72 int l,r;
73 scanf("%d%d",&l,&r);
74 printf("%d\n",Ask(l,r,1));
75 }
76 else
77 {
78 int P,val;
79 scanf("%d%d",&P,&val);
80 if(s[0]=='S')val=-val;
81 Add(P,val,1);
82 }
83 }
84 }
85 return 0;
86 }
思路：线段树模板题，更新单点区间，并且区间内保存最大值
1 #include<stdio.h>
2 #include<string>
3 #include<iostream>
4 using namespace std;
5 const int MAXN = 2e5+5;
6 int a[MAXN];
7 struct node
8 {
9 int L,R,sum,la;
10 }tree[MAXN<<2];
11 int max(int a,int b)
12 {
13 return a>b?a:b;
14 }
15 //建树
16 void Build(int L,int R,int step)
17 {
18 tree[step].L=L;tree[step].R=R;
19 if(L==R)
20 {
21 tree[step].sum=a[L];return;
22 }
23 int mid=(L+R)>>1;
24 Build(L,mid,step<<1);
25 Build(mid+1,R,step<<1|1);
26 tree[step].sum=max(tree[step<<1].sum,tree[step<<1|1].sum);
27 }
28 //单点修改
29 void Add(int P,int val,int step)
30 {
31 if(tree[step].L==tree[step].R)
32 {
33 tree[step].sum=val;return ;
34 }
35 int mid=(tree[step].L+tree[step].R)>>1;
36 if(P<=mid)Add(P,val,step<<1);
37 else Add(P,val,step<<1|1);
38 tree[step].sum=max(tree[step<<1].sum,tree[step<<1|1].sum);
39 }
40 //区间查询
41 int Ask(int L,int R,int step)
42 {
43 if(tree[step].L==L&&tree[step].R==R)return tree[step].sum;
44 int mid=(tree[step].L+tree[step].R)>>1;
45 if(R<=mid)return Ask(L,R,step<<1);
46 if(L>mid)return Ask(L,R,step<<1|1);
47 else return max(Ask(L,mid,step<<1),Ask(mid+1,R,step<<1|1));
48 }
49 int main()
50 {
51 int N,T;
52 while(~scanf("%d%d",&N,&T))
53 {
54 for(int i=1;i<=N;i++)scanf("%d",&a[i]);
55 Build(1,N,1);
56 while(T--)
57 {
58 string s;
59 cin>>s;
60 int l,r;
61 scanf("%d%d",&l,&r);
62 if(s[0]=='Q')
63 {
64 printf("%d\n",Ask(l,r,1));
65 }
66 else
67 {
68 Add(l,r,1);
69 }
70 }
71 }
72 return 0;
73 }