hdu 1698 线段树成段更新

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

#include <cstdio>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <cstring>
#include <queue>
#include <vector>

#define maxn 130050
#define lson l,mid,u<<1
#define rson mid+1,r,u<<1|1
using namespace std;

const int INF = 0x3f3f3f;

int seg[maxn<<2];
int pau[maxn<<2];

void Push_UP(int u){
    seg[u] =seg[u<<1] + seg[u<<1|1];  
}
void Push_Down(int l,int r,int u){
    if(pau[u]){
       int mid = (l + r)/2;    
       pau[u<<1]   = pau[u<<1|1] = pau[u];
       seg[u<<1]   = (mid - l + 1) * pau[u];
       seg[u<<1|1] = (r - mid) * pau[u];
       pau[u] = 0;
    }
}
void build(int l,int r,int u){
    if(l == r){
        seg[u] = 1;
        return;
    }
    int mid = (l + r)/2; 
    build(lson);
    build(rson);
    Push_UP(u);
}
void Update(int L,int R,int num,int l,int r,int u){
    if(L <= l && r <= R){  // 这个地方要注意！！ 
        pau[u] = num;   
        seg[u] = num * (r - l + 1);  
        return;
    }
    Push_Down(l,r,u);   
    int mid = (l + r)/2; 
    if(L <= mid)         Update(L,R,num,lson);
    if(R >  mid)         Update(L,R,num,rson);
    Push_UP(u);
}

int main()
{
    if(freopen("input.txt","r",stdin)== NULL)  {printf("Error
"); exit(0);}
    int T;
    cin>>T;
    for(int t=1;t<=T;t++){
        int N,Q;
        cin>>N;
        build(1,N,1);
        cin>>Q;  
        memset(pau,0,sizeof(pau));
        while(Q--){
            int X,Y,Z;
            scanf("%d%d%d",&X,&Y,&Z);
            Update(X,Y,Z,1,N,1);
        }
        printf("Case %d: The total value of the hook is %d.
",t,seg[1]);
    }
}