hdu 1698 Just a Hook

题目连接：http://acm.hdu.edu.cn/showproblem.php?pid=1698

这道题是成段更新，使用延迟标记，对于当前的left<=l&&right>=r直接返回，等到下次更新搜索到时候才向下更新，push_down;

#include<cstdio>
#include<cstdlib>
#include<cmath>
#include<cstring>
#define MAXN 200010
int color[MAXN<<2];
int tree[MAXN<<2];
void build_tree(int l,int r,int id);
void up_date_tree(int left,int right,int l,int r,int id,int value);
void push_down(int l,int r,int id);
void push_up_tree(int id);
int main()
{
    int tcase,i,j,k,n,value,left,right,num;
    while(scanf("%d",&tcase)==1)
    {
        for(j=1;j<=tcase;j++)
        {
            scanf("%d",&n);
            build_tree(1,n,1);
            scanf("%d",&num);
            for(i=0;i<num;i++)
            {

              scanf("%d%d%d",&left,&right,&value);
              up_date_tree(left,right,1,n,1,value);
            }
            printf("Case %d: The total value of the hook is %d.\n",j,tree[1]);
        }
    }

}
void build_tree(int l,int r,int id)
{
    color[id]=0;
    if(l==r)
    {
        tree[id]=1;
        return ;
    }
    tree[id]=r-l+1;
    int mid=l+r>>1;
    build_tree(l,mid,id<<1);
    build_tree(mid+1,r,id<<1|1);

}
void up_date_tree(int left,int right,int l,int r,int id,int value)
{
    if(left<=l&&right>=r)
    {
        tree[id]=(r-l+1)*value;
        color[id]=value;
        return ;
    }
    push_down(l,r,id);
    int mid=l+r>>1;
   if(left<=mid) up_date_tree(left,right,l,mid,id<<1,value);
   if(right>mid) up_date_tree(left,right,mid+1,r,id<<1|1,value);
   push_up_tree(id);
}
void push_down(int l,int r,int id)
{
    if(color[id])
    {
        color[id<<1]=color[id];
        color[id<<1|1]=color[id];
        int mid=l+r>>1;
        tree[id<<1]=(mid-l+1)*color[id];
        tree[id<<1|1]=(r-mid)*color[id];



    }
    color[id]=0;
}
void push_up_tree(int id)
{
    tree[id]=tree[id<<1]+tree[id<<1|1];
}