HDU - 1698 Just a Hook

  模板题，区间更新，把l到r区间的每个数都换成z

  

#include<stdio.h>
using namespace std;
const int maxn=100005;
struct node
{
    int l,r;
    int lazy,tag;
    int sum;
}segtree[maxn*4];
void pushdown(int i)
{
    if(segtree[i].lazy!=0)
    {

        segtree[(i<<1)].lazy=1;
        segtree[(i<<1)].tag=segtree[i].tag;
        segtree[(i<<1)].sum=(segtree[(i<<1)].r-segtree[(i<<1)].l+1)*segtree[i].tag;
        segtree[(i<<1)|1].lazy=1;
        segtree[(i<<1)|1].tag=segtree[i].tag;
        segtree[(i<<1)|1].sum=(segtree[(i<<1)|1].r-segtree[(i<<1)|1].l+1)*segtree[i].tag;
        segtree[i].lazy=0;
        segtree[i].tag=0;
    }
}
void pushup(int i)
{
    segtree[i].sum=segtree[(i<<1)].sum+segtree[(i<<1)|1].sum;
}

void build(int i,int l,int r)
{
    segtree[i].l=l;
    segtree[i].r=r;
    segtree[i].lazy=0;
    segtree[i].tag=0;
    if(l==r)
    {
        segtree[i].sum=1;
        return ;
    }
    int mid=(l+r)>>1;
    build((i<<1),l,mid);
    build((i<<1)|1,mid+1,r);
    pushup(i);
}

void update(int i,int l,int r,int v)
{
    if((segtree[i].l==l)&&(segtree[i].r==r))//³É¶Î¸üÐÂ
    {
        segtree[i].lazy=1;
        segtree[i].tag=v;
        segtree[i].sum=(r-l+1)*v;
        return ;
    }
    int mid=(segtree[i].l+segtree[i].r)>>1;
    pushdown(i);
    if(r<=mid)
        update((i<<1),l,r,v);
    else
        if(l>mid)
            update((i<<1)|1,l,r,v);
        else
        {
            update((i<<1),l,mid,v);
            update((i<<1)|1,mid+1,r,v);
        }
    pushup(i);
}


int main()
{
    int x,y,z;
    int n,m,t;
    scanf("%d",&t);
    int mycase=0;
    while(t--)
    {
        mycase++;
        scanf("%d%d",&n,&m);
        build(1,1,n);
        while(m--)
        {
            scanf("%d%d%d",&x,&y,&z);
            update(1,x,y,z);
        }
        printf("Case %d: The total value of the hook is %d.\n",mycase,segtree[1].sum);
    }

    return 0;
}