UVA 12532 Interval Product

线段树水题，忽略每个数的大小，只记住他们的正负即可，规规矩矩的代码。不过这是我第一次完全自己写的一次A的代码了。纪念一下。。。

#include <iostream>
#include <cstdio>
using namespace std;
#define N 100010

int tree[*N];
int x;
char ans[];

void build(int l,int r,int rt)
{
    if(l == r)
    {
        cin>>x;
        if(x>)
            tree[rt] = ;
        else if(x == )
            tree[rt] = ;
        else
            tree[rt] = -;
        return;
    }
    int mid = (l+r)/;
    build(l,mid,*rt);
    build(mid+,r,*rt+);
    tree[rt] = tree[*rt]*tree[*rt+];
}

void change(int l,int r,int pos,int val,int rt)
{
    if(l == r)
    {
        if(val<)
            tree[rt] = -;
        else if(val == )
            tree[rt] = ;
        else
            tree[rt] = ;
        return;
    }
    int mid = (l+r)/;
    if(pos<=mid)
        change(l,mid,pos,val,*rt);
    else
        change(mid+,r,pos,val,*rt+);
    tree[rt] = tree[*rt]*tree[*rt+];
}

int query(int l,int r,int aa,int bb,int rt)
{
    if(aa>r||bb<l)
        return ;
    if(aa<=l&&bb>=r)
        return tree[rt];
    int mid = (l+r)/;
    if(bb<=mid)
        return query(l,mid,aa,bb,*rt);
    if(aa>mid)
        return query(mid+,r,aa,bb,*rt+);
    return query(l,mid,aa,bb,*rt)*query(mid+,r,aa,bb,*rt+);
}
int main()
{
    int n,k,i,j;
    int ka;
    char ss[];
    int aa,bb;
    while(scanf("%d%d",&n,&k)!=EOF)
    {
        ka = ;
        memset(ans,,sizeof(ans));
        build(,n,);
        for(i=;i<k;i++)
        {
            scanf("%s %d %d",ss,&aa,&bb);
            if(ss[] == 'C')
            {
                change(,n,aa,bb,);
            }
            else
            {
                int res = query(,n,aa,bb,);
                if(res > )
                    ans[ka++] = '+';
                else if(res < )
                    ans[ka++] = '-';
                else
                    ans[ka++] = '';
            }
        }
        printf("%s\n",ans);
    }
    return ;
}