E - Just a Hook HDU - 1698 线段树区间修改区间和模版题

题意  给出一段初始化全为1的区间  后面可以一段一段更改成 1 或 2 或3 问最后整段区间的和是多少

思路：标准线段树区间和模版题

 #include<cstdio>
 #include<algorithm>
 #include<set>
 #include<vector>
 #include<cstring>
 #include<iostream>
 using namespace std;
 const int maxn=1e5+;
 struct Node{
     int l,r,sum;
     int lazy;
     void update(int val){
         sum=(r-l+)*val;
         lazy=val;

     }
 }tree[maxn*];
 void push_up(int x){
     tree[x].sum=tree[x<<].sum+tree[x<<|].sum;
 }
 void push_down(int x){
     if(tree[x].lazy!=){
         tree[x<<].update(tree[x].lazy);
         tree[x<<|].update(tree[x].lazy);
         tree[x].lazy=;
     }
 }
 void build(int x,int l,int r){
     tree[x].l=l,tree[x].r=r;
     tree[x].sum=tree[x].lazy=;
     if(l==r){
         tree[x].sum=;
     }
     else {
         int mid=l+r>>;
         build(x<<,l,mid);
         build(x<<|,mid+,r);
         push_down(x);
     }
 }
 void update(int x,int l,int r,int c){
     int L=tree[x].l,R=tree[x].r;
     if(R<=r&&L>=l){
         tree[x].update(c);
     }
     else {
         int mid=L+R>>;
         push_down(x);
         if(mid>=l)update(x<<,l,r,c);
         if(mid<r)update(x<<|,l,r,c);
         push_up(x);
     }
 }
 long long query(int x,int l,int r){
     int     L=tree[x].l,R=tree[x].r;
     if(R<=r&&L>=l){
         return tree[x].sum;
     }
     else {
         int mid=L+R>>;
         long long ans=;
         //push_down(x);
         if(mid>=l)ans+=query(x<<,l,r);
         if(mid<r)ans+=query(x<<|,l,r);
         return ans;
     }
 }
 int main(){
     int t,kase=;
     scanf("%d",&t);
     while(t--){
         int n,q;
         scanf("%d%d",&n,&q);
         build(,,n);
         for(int i=;i<q;i++){
             int x,y,z;
             scanf("%d%d%d",&x,&y,&z);
             update(,x,y,z);
         }
         printf("Case %d: The total value of the hook is %lld.\n",kase++,query(,,n));
     }
     return ;
 }