hdu 1166 第一道线段树，点更新

<a target=_blank href="http://acm.hdu.edu.cn/showproblem.php?pid=1166" target="_blank" style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">点击打开链接</a>

本题，拿到后我的第一想法是用数组进行维护，但是很遗憾，TLE 了，看了题解，研究了几天终于AC了。贴个代码纪念一下

<a target=_blank href="http://acm.hdu.edu.cn/showproblem.php?pid=1166" target="_blank"></a><pre name="code" class="cpp">#include<iostream>#include<cstdio>#include<algorithm>#include<string>#include<string.h>#define Max 50005*4using namespace std;struct node{    int rt;    int rson;    int lson;    int mid()    {        return (rson+lson)>>1;    }}node[Max];int ans;void build(int left,int right,int r){    node[r].lson=left;    node[r].rson=right;    if(left==right)    {        scanf("%d",&node[r].rt);        return;    }  int mid = node[r].mid();        build(left,mid,r<<1);        build(mid+1,right,r<<1|1);        node[r].rt=node[r<<1].rt+node[r<<1|1].rt;}void query(int left,int right,int r,int L,int R){    if(L<=left&&right<=R)    {        ans+=node[r].rt;        return;    }        int m=node[r].mid();        if(R<=m)            query(left,m,r<<1,L,R);        else if(m<L)            query(m+1,right,r<<1|1,L,R);        else        {            query(left,m,r<<1,L,R);            query(m+1,right,r<<1|1,L,R);        }}void update(int left,int right,int r,int pos,int add){    if(left==right)    {        node[r].rt+=add;        return;    }    int mid = node[r].mid();    if(pos<=mid)        update(left,mid,r<<1,pos,add);    else        update(mid+1,right,r<<1|1,pos,add);    node[r].rt=node[r<<1].rt+node[r<<1|1].rt;}int main(){    int t;    scanf("%d",&t);    for(int z=1;z<=t;z++)    {        int n;        printf("Case %d:\n",z);        scanf("%d",&n);        build(1,n,1);        char op[30];        int a,b;        while(scanf("%s",op))        {            if(op[0]=='E') break;            scanf("%d %d",&a,&b);            if(op[0]=='Q')            {                ans=0;                query(1,n,1,a,b);                printf("%d\n",ans);            }            else if(op[0]=='A')                update(1,n,1,a,b);            else update(1,n,1,a,-1*b);        }    }    return 0;}