Hdu 1968 Just a Hook

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题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=1698

前几题练习单点更新，现在练习成段更新。

线段树成段更新，需要用到延迟标记。

其实延迟标记又分为完成时标记与未完成标记，我们只练习前者。

#include <iostream>#include <stdio.h>#include <stdlib.h>#include <string.h>#include <math.h>#include <map>#include <queue>#include <algorithm>using namespace std;#define Maxn 100005#define lx (x<<1)#define rx ((x<<1) | 1)#define MID ((l + r)>>1)int A[Maxn];int S[Maxn<<2];int D[Maxn<<2];void pushUp(int x){    S[x] = S[lx] + S[rx];}void pushDown(int l,int r,int x){    if(D[x])    {        D[lx] = D[x];        D[rx] = D[x];        S[lx] = (MID-l+1)*D[x];        S[rx] = (r-MID)*D[x];        D[x] = 0;    }}void build(int l,int r,int x){    D[x] = 0;    if(l == r)    {        S[x] = 1;        return;    }    build(l,MID,lx);    build(MID+1,r,rx);    pushUp(x);}int query(int L,int R,int l,int r,int x){    int ans = 0;    if(L<=l && r<=R)    {        return S[x];    }    pushDown(l,r,x);    if(L<=MID) ans += query(L,R,l,MID,lx);    if(R>=MID+1) ans += query(L,R,MID+1,r,rx);    return ans;}void update(int L,int R,int d,int l,int r,int x){    if(L<=l && r<=R)    {        D[x] = d;        S[x] = (r - l + 1)*d;        return;    }    pushDown(l,r,x);    if(L<=MID) update(L,R,d,l,MID,lx);    if(MID+1<=R) update(L,R,d,MID+1,r,rx);    pushUp(x);}int main(){#ifndef ONLINE_JUDGE    freopen("in.txt","r",stdin);#endif    int t;    int n;    int q;    int x,y,kind;    int cas = 0;    scanf(" %d",&t);    while(t--)    {        cas++;        scanf(" %d",&n);        build(1,n,1);        scanf(" %d",&q);        while(q--)        {            scanf(" %d %d %d",&x,&y,&kind);            update(x,y,kind,1,n,1);        }        int ans = query(1,n,1,n,1);        printf("Case %d: The total value of the hook is %d.\n",cas,ans);    }    return 0;}