In the game of DotA, Pudge’s meat hook is actually the most horrible thing for most of the heroes. The hook is made up of several consecutive metallic sticks which are of the same length.
Now Pudge wants to do some operations on the hook.
Let us number the consecutive metallic sticks of the hook from 1 to N. For each operation, Pudge can change the consecutive metallic sticks, numbered from X to Y, into cupreous sticks, silver sticks or golden sticks.
The total value of the hook is calculated as the sum of values of N metallic sticks. More precisely, the value for each kind of stick is calculated as follows:
For each cupreous stick, the value is 1.
For each silver stick, the value is 2.
For each golden stick, the value is 3.
Pudge wants to know the total value of the hook after performing the operations.
You may consider the original hook is made up of cupreous sticks.
题意：描述了一个屠夫，它的肉钩有N节，每节价值是1~3，它可以成段修改它的肉钩的价值，问修改若干次后肉钩的总价值是多少
线段树裸题，区间改值与查询总权值和。
1 #include<stdio.h>
2 #include<string.h>
3 const int maxm=100005;
4 int st[maxm<<2],cha[maxm<<2];
5
6 int read(){
7 int x=0;
8 char c=getchar();
9 while(c>'9'||c<'0')c=getchar();
10 while(c>='0'&&c<='9'){
11 x=x*10+c-'0';
12 c=getchar();
13 }
14 return x;
15 }
16
17 void build(int o,int l,int r){
18 if(l==r){st[o]=1;return;}
19 int m=l+((r-l)>>1);
20 build(o<<1,l,m);
21 build(o<<1|1,m+1,r);
22 st[o]=st[o<<1]+st[o<<1|1];
23 }
24
25 void pushup(int o){
26 st[o]=st[o<<1]+st[o<<1|1];
27 }
28
29 void pushdown(int o,int l,int r){
30 if(cha[o]){
31 cha[o<<1]=cha[o];
32 cha[o<<1|1]=cha[o];
33 int m=l+((r-l)>>1);
34 st[o<<1]=cha[o]*(m-l+1);
35 st[o<<1|1]=cha[o]*(r-m);
36 cha[o]=0;
37 }
38 }
39
40 void update(int o,int l,int r,int ql,int qr,int c){
41 if(ql<=l&&qr>=r){
42 cha[o]=c;
43 st[o]=c*(r-l+1);
44 return;
45 }
46 pushdown(o,l,r);
47 int m=l+((r-l)>>1);
48 if(ql<=m)update(o<<1,l,m,ql,qr,c);
49 if(qr>=m+1)update(o<<1|1,m+1,r,ql,qr,c);
50 pushup(o);
51 }
52
53 int main(){
54 int T=read();
55 for(int q=1;q<=T;q++){
56 memset(cha,0,sizeof(cha));
57 int n=read();
58 build(1,1,n);
59 int m=read();
60 for(int i=1;i<=m;i++){
61 int ql=read();
62 int qr=read();
63 int c=read();
64 update(1,1,n,ql,qr,c);
65 }
66 printf("Case %d: The total value of the hook is %d.
",q,st[1]);
67 }
68 return 0;
69 }