北大zhw大神bzoj1756代码

#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <algorithm>
using namespace std;
int tree[][],a[],n,m,A,B,C,i,ans,t,x;
void Update(int x)
{
    tree[x][]=tree[x*][]+tree[x*+][];
    tree[x][]=max(tree[x*][],tree[x*+][]);
    tree[x][]=max(tree[x*][],tree[x*][]+tree[x*+][]);
    tree[x][]=max(tree[x*+][],tree[x*+][]+tree[x*][]);
    tree[x][]=max(max(tree[x*][],tree[x*+][]),tree[x*][]+tree[x*+][]);
}
int WORK(int root,int l,int r)
{
    if (tree[root][]==l && tree[root][]==r) return tree[root][];
    int mid=(tree[root][]+tree[root][])/,p=-,q=-;
    if (l<=mid) p=WORK(root*,l,min(mid,r));
    if (r>mid) q=WORK(root*+,max(l,mid+),r);
    return max(p,q);
}
void work(int root,int l,int r)
{
    if (tree[root][]==l && tree[root][]==r)
    {
        ans=max(ans,tree[root][]+t);
        ans=max(ans,tree[root][]);
        t=max(t+tree[root][],tree[root][]);
        t=max(t,);
        return;
    }
    int mid=(tree[root][]+tree[root][])/;
    if (l<=mid) work(root*,l,min(mid,r));
    if (r>mid) work(root*+,max(mid+,l),r);
}
int main()
{
    scanf("%d%d",&n,&m);
    for (i=; i<=n; i++) scanf("%d",&a[i]);
    for (i=; i<=; i++)
    {
        tree[i][]=tree[i][]=i;
        tree[i][]=tree[i][]=a[i-];
        tree[i][]=tree[i][]=tree[i][]=max(a[i-],);
    }
    for (i=; i>=; i--)
    {
        tree[i][]=tree[i*][];
        tree[i][]=tree[i*+][];
        Update(i);
    }
    for (i=; i<=m; i++)
    {
        scanf("%d%d%d",&A,&B,&C);
        if (A==)
        {
            x=+B;
            tree[x][]=tree[x][]=C;
            tree[x][]=tree[x][]=tree[x][]=max(C,);
            while (x!=)
            {
                x/=;
                Update(x);
            }
        }
        else
        {
            if (B>C) swap(B,C);
            t=;
            ans=WORK(,B+,C+);
            if (ans<) printf("%d\n",ans); else
            {
                work(,B+,C+);
                printf("%d\n",ans);
            }
        }
    }
    return ;
}