Submission #977049

#	Time	Username	Problem	Language	Result	Execution time	Memory
977049		SeenSiravit	Ice Hockey World Championship (CEOI15_bobek)	C++14	40 / 100	68 ms	8936 KiB

bobek

#include<bits/stdc++.h>
#define ll long long

using namespace std;

const int mxN = 40 + 5 , mxM = 1e6 + 5;

int n;
ll m;
ll a[mxN];

void bruteforce(){
    // sub 1-4
    ll ans = 0;
    ll lim = 1<<n;


    for(int mask=0;mask<lim;mask++){
        ll sum = 0;

        for(int i=0;i<n;i++){
            if((1<<i) & mask) sum += a[i];
            if(sum > m) break;
        }

        if(sum <= m) ans++;
    }

    cout<< ans;
}

ll fw[mxM];

void update(int idx , int val){
    for(int i=idx;i<=m;i += (i & -i)) fw[i] += val;
}

int query(int idx){
    int cnt = 0;
    for(int i=idx;i>0;i -= (i & -i)) cnt += fw[i];
    return cnt;
}

void bruteforce2(){

    update(1 , 1);

    ll ans = 1;

    for(int i=0;i<n;i++){
        ll rm = m - a[i] + 1;

        int cnt = (rm<=0 ? 0 : query(rm));

        if(rm>0) update(a[i]+1 , 1);

        // cout<< i << " : " << cnt << "\n";
        ans += cnt;

        // for(int j=0;j<=m;j++) cout<< fw[j] << " ";
        // cout<< "\n";
    }

    cout<< ans;
}

int main(){
    ios::sync_with_stdio(0),cin.tie(0);

    cin>> n >> m;

    for(int i=0;i<n;i++) cin>> a[i];

    if(n<=20) bruteforce();
    else bruteforce2();


    return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 10 / 10
• Subtask 5: 0 / 10
• Subtask 6: 0 / 10
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10
• Subtask 10: 0 / 10