HDU1698 Just a Hook

#include<iostream>
#include<queue>
#include<map>
#include<vector>
#include<cstdio>
#include<algorithm>
#include<stack>
#include<string>
#include<cstring>
using namespace std;
typedef long long ll;
const int N=1e5+10;
const int inf=0x3f3f3f3f;
struct node{
    int l,r;
    int sum;
    int lazy;
}tr[N<<2];
void pushup(int u){
    tr[u].sum=tr[u<<1].sum+tr[u<<1|1].sum;
}
void build(int u,int l,int r){
    if(l==r){
        tr[u]={l,l,1,0};

    }
    else{
        int mid=l+r>>1;
        tr[u]={l,r,0,0};
        build(u<<1,l,mid);
        build(u<<1|1,mid+1,r);
        pushup(u);
    }
}
void pushdown(int u){
    if(tr[u].lazy){
        tr[u<<1].lazy=tr[u<<1|1].lazy=tr[u].lazy;
        tr[u<<1].sum=(tr[u<<1].r-tr[u<<1].l+1)*tr[u].lazy;
        tr[u<<1|1].sum=(tr[u<<1|1].r-tr[u<<1|1].l+1)*tr[u].lazy;
        tr[u].lazy=0;
    }
}
void modify(int u,int l,int r,int x){
    if(tr[u].l>=l&&tr[u].r<=r){
        tr[u].sum=(tr[u].r-tr[u].l+1)*x;
        tr[u].lazy=x;
        return ;
    }
    pushdown(u);
    int mid=tr[u].l+tr[u].r>>1;
    if(l<=mid)
        modify(u<<1,l,r,x);
    if(r>mid)
        modify(u<<1|1,l,r,x);
    pushup(u);
}
int main(){
    int t;
    int n;
    cin>>t;
    int cnt=1;
    while(t--){
        cin>>n;
        int m;
        cin>>m;
        int i;
        build(1,1,n);
        for(i=1;i<=m;i++){
            int x,y,z;
            scanf("%d%d%d",&x,&y,&z);
            modify(1,x,y,z);
        }
        printf("Case %d: The total value of the hook is %d.\n",cnt++,tr[1].sum);
    }
}