【树状数组】【2019hdu多校】Find the answer
题意:每次从1到i-1中选择最少的数减为0,确保1到i的前缀和小于m,我们离散化,从小到大排序,按照输入顺序每遍历一个就插入到树状数组在排序过后的位置,二分位置确保树状数组的前缀和刚好小于/等于m-a[i](当前i必选),因为从小到大排序确保了现有的小的尽量多选,大的都删掉。
#include<bits/stdc++.h>
#define ll long long
#define ull unsigned long long
using namespace std;
const int N = 200000 + 5;
int q,n;
ll m;
struct node
{
int num;
ll sum;
}c[200005];
struct nod
{
int id;
ll w;
}a[200005];
int mp[200005];
bool cmp(nod a,nod b)
{
if(a.w==b.w)
return a.id<b.id;
return a.w<b.w;
}
void add(int x,ll y)
{
for(;x<=n;x+=x&-x)
{
c[x].sum+=y;
c[x].num++;
}
}
ll ask_sum(int x)
{
ll ret=0;
for(;x;x-=x&-x)
{
ret+=c[x].sum;
//cout<<x<<endl;
}
return ret;
}
ll ask_num(int x)
{
ll ret=0;
for(;x;x-=x&-x)
{
ret+=c[x].num;
}
return ret;
}
int half_find(ll x)
{
int l=0,r=n;
int mid=(l+r)>>1;
while(l<=r)
{
//cout<<mid<<endl;
mid=(l+r)>>1;
if(ask_sum(mid)>x)
{
r=mid-1;
}
else
{
l=mid+1;
}
//cout<<l<<" "<<r<<" "<<mid<<endl;
}
//cout<<r<<endl;
return ask_num(r);
}
int main()
{
int x=3;
//for(;x;x-=x&-x)
//cout<<x<<endl;
scanf("%d",&q);
//cout<<ask_num(7)<<endl;
while(q--)
{
scanf("%d %lld",&n,&m);
for(int i=1;i<=n;i++)
{
scanf("%lld",&a[i].w);
a[i].id=i;
c[i].num=c[i].sum=0;
}
sort(a+1,a+n+1,cmp);
for(int i=1;i<=n;i++)
{
//cout<<a[i].id<<endl;
mp[a[i].id]=i;
}
printf("0");
add(mp[1],a[mp[1]].w);
for(int i=2;i<=n;i++)
{
printf(" %lld",i-1-half_find(m-a[mp[i]].w));
add(mp[i],a[mp[i]].w);
}
printf("\n");
}
return 0;
}