AC日记——绿色通道 codevs 3342

#include <cstdio>
#include <iostream>
#include <algorithm>

#define maxn 50005

using namespace std;

struct TreeNodeType {
    int l,r,dis,mid;
};
struct TreeNodeType tree[maxn<<2];

int if_z,n,t,cost[maxn],ans;

char Cget;

inline void read_int(int &now)
{
    now=0,if_z=1,Cget=getchar();
    while(Cget>‘9‘||Cget<‘0‘)
    {
        if(Cget==‘-‘) if_z=-1;
        Cget=getchar();
    }
    while(Cget>=‘0‘&&Cget<=‘9‘)
    {
        now=now*10+Cget-‘0‘;
        Cget=getchar();
    }
    now*=if_z;
}

void tree_build(int now,int l,int r)
{
    tree[now].l=l,tree[now].r=r;
    if(l==r) return ;
    tree[now].mid=(l+r)>>1;
    tree_build(now<<1,l,tree[now].mid);
    tree_build(now<<1|1,tree[now].mid+1,r);
}

inline void tree_up(int now)
{
    tree[now].dis=min(tree[now<<1].dis,tree[now<<1|1].dis);
}

void tree_start(int now)
{
    tree[now].dis=0;
    if(tree[now].l==tree[now].r) return ;
    tree_start(now<<1),tree_start(now<<1|1);
}

void tree_change(int now,int to,int x)
{
    if(tree[now].l==tree[now].r&&tree[now].l==to)
    {
        tree[now].dis=x;
        return ;
    }
    if(to<=tree[now].mid) tree_change(now<<1,to,x);
    else tree_change(now<<1|1,to,x);
    tree_up(now);
}

int tree_query(int now,int l,int r)
{
    if(tree[now].l==l&&tree[now].r==r)
    {
        return tree[now].dis;
    }
    if(l>tree[now].mid) return tree_query(now<<1|1,l,r);
    else if(r<=tree[now].mid) return tree_query(now<<1,l,r);
    else
    {
        return min(tree_query(now<<1,l,tree[now].mid),tree_query(now<<1|1,tree[now].mid+1,r));
    }
}

void tree_check(int now)
{
    if(tree[now].l==tree[now].r)
    {
        printf("%d ",tree[now].dis);
        return ;
    }
    tree_check(now<<1);tree_check(now<<1|1);
}

bool check(int size)
{
    size++;
    tree_start(1);
    for(int i=1;i<=n+1;i++)
    tree_change(1,i,tree_query(1,max(0,i-size),i-1)+cost[i]);
    //tree_check(1);
    //printf("\n");
    int pos=tree_query(1,n+1,n+1);
    if(pos<=t) return true;
    else return false;
}

int main()
{
    read_int(n),read_int(t);
    for(int i=1;i<=n;i++) read_int(cost[i]);
    int lit=1,rit=n,mid;
    ans=n;
    tree_build(1,0,n+1);
    while(lit<=rit)
    {
        mid=(lit+rit)>>1;
        if(check(mid))
        {
            rit=mid-1;
            ans=mid;
        }
        else lit=mid+1;
    }
    printf("%d\n",ans);
    return 0;
}