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];

}