hdu1698Just a Hook

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http://acm.hdu.edu.cn/showproblem.php?pid=1698
裸的线段树区间更新

#include <iostream>#include <algorithm>#include <cstdio>#include <cstring>using namespace std;const int maxn=100005;struct Node{    int sum,lazy;}node[maxn<<2];void pushup(int rt){    node[rt].sum=node[rt<<1].sum+node[rt<<1|1].sum;}void pushdown(int rt,int len){    if(node[rt].lazy)    {        node[rt<<1].lazy=node[rt].lazy;        node[rt<<1|1].lazy=node[rt].lazy;        node[rt<<1].sum=node[rt].lazy*(len-(len>>1));        node[rt<<1|1].sum=node[rt].lazy*(len>>1);        node[rt].lazy=0;//注意更新    }}void build(int l,int r,int rt){    node[rt].lazy=0;    if(l==r)    {        node[rt].sum=1;        return ;    }    int m=(l+r)>>1;    build(l,m,rt<<1);    build(m+1,r,rt<<1|1);    pushup(rt);}void update(int ll,int rr,int add,int l,int r,int rt){    if(ll<=l&&rr>=r)    {        node[rt].sum=add*(r-l+1);        node[rt].lazy=add;        return ;    }    pushdown(rt,r-l+1);    int m=(l+r)>>1;    if(ll<=m)    update(ll,rr,add,l,m,rt<<1);    if(rr>m)    update(ll,rr,add,m+1,r,rt<<1|1);    pushup(rt);}int main(){    int T,t=1,n,m;    scanf("%d",&T);    while(T--)    {        scanf("%d%d",&n,&m);        int a,b,c;        build(1,n,1);        while(m--)        {            scanf("%d%d%d",&a,&b,&c);            update(a,b,c,1,n,1);        }        printf("Case %d: The total value of the hook is %d.\n",t++,node[1].sum);    }    return 0;}

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