HDU 1689 Just a Hook（线段是 区间更新+区间求和）

Posted 2020-10-09

题目链接：http://acm.split.hdu.edu.cn/showproblem.php?pid=1698

题意：用1，2，3三种价值的颜色去给棒子区间涂色，问最后整个棒子的价值为多少，一开始整个都涂上价值为1的颜色

题解：区间更新 区间求和

 1 //HDU 1689 Just a Hook
 2 //区间更新 区间求和 
 3 #include <cstdio>
 4 #include <iostream>
 5 #include <algorithm>
 6 using namespace std; 
 7 
 8 typedef long long LL;
 9 const int MAX=100000+10;
10 LL n,m;
11 
12 struct Tree
13 {
14     LL l,r;
15     LL sum,idx;
16 };
17 Tree tree[4*MAX];
18 
19 void pushup(LL x) //向上更新 
20 {
21     LL tmp=x<<1;
22     tree[x].sum=tree[tmp].sum+tree[tmp+1].sum;
23 }
24 
25 void pushdown(LL x) //向下更新 
26 {
27     LL tmp=x<<1;
28     tree[tmp].idx=tree[x].idx;
29     tree[tmp+1].idx=tree[x].idx;
30     tree[tmp].sum=tree[x].idx*(tree[tmp].r-tree[tmp].l+1);
31     tree[tmp+1].sum=tree[x].idx*(tree[tmp+1].r-tree[tmp+1].l+1);
32     tree[x].idx=0;
33 }
34 
35 void build(LL l,LL r,LL x)
36 {
37     tree[x].l=l;
38     tree[x].r=r;
39     tree[x].idx=0;
40     if(l==r)
41     {
42         tree[x].sum=1;
43         return ;
44     }    
45     LL tmp=x<<1;
46     LL mid=(l+r)>>1;
47     build(l,mid,tmp);
48     build(mid+1,r,tmp+1);
49     pushup(x);
50 }
51 
52 void update(LL l,LL r,LL c,LL x)
53 {
54     if(r<tree[x].l||l>tree[x].r) return ;
55     if(l<=tree[x].l&&r>=tree[x].r)
56     {
57         tree[x].idx=c;
58         tree[x].sum=c*(tree[x].r-tree[x].l+1);
59         return ;    
60     }
61     if(tree[x].idx) pushdown(x);
62     LL tmp=x<<1;
63     update(l,r,c,tmp);
64     update(l,r,c,tmp+1);
65     pushup(x);
66 }
67 
68 int main(){
69     LL t,A,B,C;
70     scanf("%lld",&t);
71     for(int k=1;k<=t;k++){
72         scanf("%lld",&n);
73         scanf("%lld",&m);
74         build(1,n,1);
75         for(int i=1;i<=m;i++){
76             scanf("%lld%lld%lld",&A,&B,&C);
77             update(A,B,C,1);
78         }
79         printf("Case %d: The total value of the hook is %lld.\n",k,tree[1].sum);
80     } 
81     return 0;
82 }