In this HackerEarth Good Evening sweetheart!![Medium] problem solution Scube sold you N candles, for each candle i you know its height. Using a candle during one evening decreases the candle height by 1. You plan to have at most M romantic evenings. For each evening i you know the number of candles C[i] you want to lit. Find a strategy of lighting the candles in order to maximize the number of evenings you can spend. You are forced to stop after the night i when you can't light C[i] candles.


HackerEarth Good Evening sweetheart!![Medium] problem solution


HackerEarth Good Evening sweetheart!![Medium] problem solution.

include<bits/stdc++.h>
using namespace std;
#define int long long
#define rep(i,n) for(int i=0;i<(n);i++)
#define pb push_back
#define all(v) (v).begin(),(v).end()
#define fi first
#define se second
typedef vector<int>vint;
typedef pair<int,int>pint;
typedef vector<pint>vpint;
template<typename A,typename B>inline void chmin(A &a,B b){if(a>b)a=b;}
template<typename A,typename B>inline void chmax(A &a,B b){if(a<b)a=b;}
struct segtree{
static const int SEG=1<<17;
vint dat,put;
segtree():dat(SEG*2),put(SEG*2){}
inline void push(int k,int l,int r){
dat[k]+=put[k]*(r-l);
if(k<SEG-1){
put[k*2+1]+=put[k];
put[k*2+2]+=put[k];
}
put[k]=0;
}
void update(int a,int b,int x,int k=0,int l=0,int r=SEG){
push(k,l,r);
if(r<=a|b<=l)return;
if(a<=l&&r<=b){
put[k]+=x;
push(k,l,r);
return;
}
update(a,b,x,k*2+1,l,(l+r)/2);
update(a,b,x,k*2+2,(l+r)/2,r);
dat[k]=dat[k*2+1]+dat[k*2+2];
}
int query(int a,int b,int k=0,int l=0,int r=SEG){
push(k,l,r);
if(r<=a||b<=l)return 0;
if(a<=l&&r<=b)return dat[k];
return query(a,b,k*2+1,l,(l+r)/2)
+query(a,b,k*2+2,(l+r)/2,r);
}
};
int N,M;
int H[111111],C[111111];
signed main(){
cin>>N>>M;
rep(i,N)cin>>H[i];
rep(i,M)cin>>C[i];
sort(H,H+N);
segtree seg;
rep(i,N)seg.update(i,i+1,H[i]);
rep(i,M){
int x=seg.query(N-C[i],N-C[i]+1);
int lb=-1,ub=N-C[i];
while(ub-lb>1){
int mid=(ub+lb)/2;
if(seg.query(mid,mid+1)==x)ub=mid;
else lb=mid;
}
int l=ub;

lb=N-C[i],ub=N;
while(ub-lb>1){
int mid=(ub+lb)/2;
if(seg.query(mid,mid+1)==x)lb=mid;
else ub=mid;
}
int r=ub;
if(x==0){
cout<<i<<endl;
return 0;
}
seg.update(r,N,-1);
seg.update(l,l+C[i]-(N-r),-1);
}
cout<<M<<endl;
}