E - Just a Hook HDU - 1698——线段树区间更新+lazy标记

Think:
1知识点：线段树区间更新+lazy标记
2题意：在n个初始化点权为1的点的基础上进行区间更新，询问最终状态n个点的点权之和
3反思：当前题目lazy标记赋值更新

vjudge题目链接

以下为Wrong Answer代码——lazy标记更新错误

#include 
#include 
#include 

using namespace std;

const int N = 101400;

struct Node{
    int sum;
}node[N<<2];

int lazy[N<<2];

void Build(int l, int r, int rt);
void Updata(int rt);
void down(int rt, int l, int r);
void up_v(int L, int R, int v, int l, int r, int rt);

int main(){
    int T, k = 1, n, m, L, R, v;
    scanf("%d", &T);
    while(T--){
        scanf("%d", &n);
        Build(1, n, 1);
        scanf("%d", &m);
        while(m--){
            scanf("%d %d %d", &L, &R, &v);
            up_v(L, R, v, 1, n, 1);
        }
        printf("Case %d: The total value of the hook is %d.\n", k++, node[1].sum);
    }
    return 0;
}
void Build(int l, int r, int rt){
    lazy[rt] = 0;
    if(l == r){
        node[rt].sum = 1;
        return;
    }
    int mid = (l+r)/2;
    Build(l, mid, rt<<1);
    Build(mid+1, r, rt<<1|1);
    Updata(rt);
}
void Updata(int rt){
    node[rt].sum = node[rt<<1].sum + node[rt<<1|1].sum;
}
void up_v(int L, int R, int v, int l, int r, int rt){
    if(L <= l && r <= R){
        node[rt].sum = v*(r-l+1);
        lazy[rt] = v;
        return;
    }
    down(rt, l, r);
    int mid = (l+r)/2;
    if(L <= mid)
        up_v(L, R, v, l, mid, rt<<1);
    if(R > mid)
        up_v(L, R, v, mid+1, r, rt<<1|1);
    Updata(rt);
}
void down(int rt, int l, int r){
    if(lazy[rt]){
        lazy[rt<<1] += lazy[rt];
        lazy[rt<<1|1] += lazy[rt];
        int mid = (l+r)/2;
        node[rt<<1].sum = lazy[rt]*(mid-l+1);
        node[rt<<1|1].sum = lazy[rt]*(r-mid);
        lazy[rt] = 0;
    }
}

以下为Accepted代码

#include 
#include 
#include 

using namespace std;

const int N = 101400;

struct Node{
    int sum;
}node[N<<2];

int lazy[N<<2];

void Build(int l, int r, int rt);
void Updata(int rt);
void down(int rt, int l, int r);
void up_v(int L, int R, int v, int l, int r, int rt);

int main(){
    int T, k = 1, n, m, L, R, v;
    scanf("%d", &T);
    while(T--){
        scanf("%d", &n);
        Build(1, n, 1);
        scanf("%d", &m);
        while(m--){
            scanf("%d %d %d", &L, &R, &v);
            up_v(L, R, v, 1, n, 1);
        }
        printf("Case %d: The total value of the hook is %d.\n", k++, node[1].sum);
    }
    return 0;
}
void Build(int l, int r, int rt){
    lazy[rt] = 0;
    if(l == r){
        node[rt].sum = 1;
        return;
    }
    int mid = (l+r)/2;
    Build(l, mid, rt<<1);
    Build(mid+1, r, rt<<1|1);
    Updata(rt);
}
void Updata(int rt){
    node[rt].sum = node[rt<<1].sum + node[rt<<1|1].sum;
}
void up_v(int L, int R, int v, int l, int r, int rt){
    if(L <= l && r <= R){
        node[rt].sum = v*(r-l+1);
        lazy[rt] = v;
        return;
    }
    down(rt, l, r);
    int mid = (l+r)/2;
    if(L <= mid)
        up_v(L, R, v, l, mid, rt<<1);
    if(R > mid)
        up_v(L, R, v, mid+1, r, rt<<1|1);
    Updata(rt);
}
void down(int rt, int l, int r){
    if(lazy[rt]){
        lazy[rt<<1] = lazy[rt];/*lazy标记赋值更新*/
        lazy[rt<<1|1] = lazy[rt];/*lazy标记赋值更新*/
        int mid = (l+r)/2;
        node[rt<<1].sum = lazy[rt]*(mid-l+1);
        node[rt<<1|1].sum = lazy[rt]*(r-mid);
        lazy[rt] = 0;
    }
}