基礎的線段樹成段更新，學習了notonlysuccess dalao的程式碼後寫的

#include<iostream>
#include<cstdio>
#include<cstring>
#include<ctime>
#include<algorithm>
#include<cstdlib>
#include<cmath>
#include<set>
#include<bitset>
#include<map>
#include<stack>
#include<queue>
#include<vector>
#include<utility>
#define INF 0x3f3f3f3f
#define inf 2*0x3f3f3f3f
#define llinf 1000000000000000000
#define pi acos(-1)
#define mod 1000000007
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
using namespace std;
typedef long long ll;
typedef pair<int,int>P;
int col[100005*4],sum[100005*4],t,n,q,x,y,z;
void pushup(int rt)
{
    sum[rt]=sum[rt<<1]+sum[rt<<1|1];
}
void pushdown(int rt,int m)
{
    if (col[rt]) {
              col[rt<<1] = col[rt<<1|1] = col[rt];
              sum[rt<<1] = (m - (m >> 1)) * col[rt];
              sum[rt<<1|1] = (m >> 1) * col[rt];
              col[rt] = 0;
    }
}
void build(int l,int r,int rt)
{
    col[rt]=0;
    sum[rt]=1;
    if(l==r)return ;
    int m=(l+r)>>1;
    build(lson);build(rson);
    pushup(rt);
}
void change(int L,int R,int x,int l,int r,int rt)
{
    if (L <= l && r <= R) {
              col[rt] = x;
              sum[rt] = x * (r - l + 1);
              return ;
    }
    pushdown(rt,r-l+1);
    int m=(l+r)>>1;
    if(L<=m)change(L,R,x,lson);
    if(R>m)change(L,R,x,rson);
    pushup(rt);
}
int main()
{
    cin>>t;
    for(int ca=1;ca<=t;ca++)
    {
        scanf("%d%d",&n,&q);
        build(1,n,1);
        while(q--)
        {
            scanf("%d%d%d",&x,&y,&z);
            change(x,y,z,1,n,1);
        }
        printf("Case %d: The total value of the hook is %d.\n",ca,sum[1]);
    }
    return 0;
}