HDU-1698-Just a Hook

#include <iostream>
#include <memory.h>
#include <vector>
#include <map>
#include <algorithm>

using namespace std;

typedef long long LL;

const int MAXN = 1e5 + 10;
int segments[MAXN * 4];
int add[MAXN * 4];

void Push_down(int root, int l, int r)
{
    if (add[root])
    {
        add[root << 1] = add[root];
        add[root << 1 | 1] = add[root];
        int mid = (l + r) / 2;
        segments[root << 1] = add[root] * (mid - l + 1);
        segments[root << 1 | 1] = add[root] * (r - mid);
        add[root] = 0;
    }
}

void Build_tree(int root, int l, int r)
{
    if (l == r)
    {
        segments[root] = 1;
        return ;
    }
    int mid = (l + r) / 2;
    Build_tree(root << 1, l, mid);
    Build_tree(root << 1 | 1, mid + 1, r);
    segments[root] = segments[root << 1] + segments[root << 1 | 1];
}

void Update_tree(int root, int l, int r, int ql, int qr, int c)
{
    if (ql > r || qr < l)
        return ;
    if (ql <= l && r <= qr)
    {
        segments[root] = (r - l + 1) * c;
        add[root] = c;
    }
    else
    {
        Push_down(root, l, r);
        int mid = (l + r) / 2;
        Update_tree(root << 1, l, mid, ql, qr, c);
        Update_tree(root << 1 | 1, mid + 1, r, ql, qr, c);
        segments[root] = segments[root << 1] + segments[root << 1 | 1];
    }
}

int Query(int root, int l, int r, int w)
{
    if (l == r)
        return segments[root];
    int mid = (l + r) / 2;
    if (w <= mid)
        return Query(root << 1, l, mid, w);
    else
        return Query(root << 1 | 1, mid + 1, r, w);
}

int main()
{
    int t, cnt = 0;
    scanf("%d", &t);
    while (t--)
    {
        int n, q;
        int l, r, op;
        scanf("%d%d", &n, &q);
        Build_tree(1, 1, n);
        memset(add, 0, sizeof(add));

        for (int i = 1;i <= q;i++)
        {
            scanf("%d%d%d", &l, &r, &op);
            Update_tree(1, 1, n, l, r, op);
        }
        printf("Case %d: The total value of the hook is %d.\n", ++cnt, segments[1]);
    }

    return 0;
}