HDU - 1698 Just a Hook

#include<iostream>
#include<stdio.h>
using namespace std;

struct node{
	int left,right,value,type;
	void change(int num)
	{
		value = (right - left + 1) * num;
		type = num;
	}
};

struct segtree{
	node tree[400000];
	void bulid(int st,int ed,int x)//建树 
	{
		tree[x].left = st; tree[x].right = ed; //确定左区间和右区间 
		tree[x].value = ed - st + 1;
		tree[x].type = 1;
		int mid = st + (ed - st) / 2; 
		if (st == ed) return;
		bulid(st,mid,x * 2);
		bulid(mid + 1,ed,x * 2 + 1);
	}
	void insert(int st,int ed,int x,int num)
	{
		if (st<=tree[x].left && ed>=tree[x].right) tree[x].change(num);
		else
		{
			if (tree[x].type != 0)//lazy标志下移 
			{
				tree[x * 2].change(tree[x].type);
				tree[x * 2 + 1].change(tree[x].type);
				tree[x].type = 0;
			}
			int mid = (tree[x].right - tree[x].left) / 2 + tree[x].left;
			if (st <= mid) insert(st,ed,x * 2,num);
			if (ed > mid) insert(st,ed,x * 2 + 1,num);
			tree[x].value = tree[x * 2 + 1].value + tree[x * 2].value;
		}
	}
	int value()
	{
		return tree[1].value;
	}
}seg;

int main()
{
	int p,count = 0;
	cin>>p;
	while (p--)
	{
		int n,m;
		cin>>n>>m;
		seg.bulid(1,n,1);
		while (m--)
		{
			int x,y,z;
			scanf("%d%d%d",&x,&y,&z);
			seg.insert(x,y,1,z);
		}
		printf("Case %d: The total value of the hook is %d.\n",++count,seg.value());
	}
}

蒟蒻的线段树学习之旅…（空了那么久才做题，没脸见人了，orz）