Submission #467681

#	Time	Username	Problem	Language	Result	Execution time	Memory
467681		LptN21	Savrsen (COCI17_savrsen)	C++14	120 / 120	513 ms	81320 KiB

savrsen

#include <bits/stdc++.h>
using namespace std;
#define fastIO ios_base::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL)
#define PI acos(-1.0)
#define FF first
#define SS second
// vector
#define pb push_back
#define sz(v) int((v).size())
#define all(v) (v).begin(), (v).end()
#define lb lower_bound
#define ub upper_bound
// bit
#define CNTBIT(x) __builtin_popcount(x)
#define ODDBIT(x) __builtin_parity(x)
#define MASK(i) (1<<(i))
#define BIT(x, i) (((x)>>(i))&1)
#define SUBSET(big, small) (((big)&(small))==(small))
// typedef
typedef long long ll;
typedef long double ld;
typedef pair<int, int> ii;
typedef pair<ll, ii> i3;
/* CODE BELOW */
const int N=1e7+7, M=30000+7, K=3;
const int MOD=1e9+7;
const ll oo=1e18+7;

int n, m, k, t;

int lp[N];
vector<int> pr;
int p[N];

void sieve(int n) {
    for(int i=2;i<=n;i++) {
        if(!lp[i]) pr.pb(lp[i]=i);
        for(int j=0;j<sz(pr)&&pr[j]<=lp[i]
                    &&pr[j]*i<=n;j++)
            lp[i*pr[j]]=pr[j];
    }
}

signed main() {
    //freopen("test.inp", "r", stdin);
    //freopen("test.out", "w", stdout);
    //fastIO;
    scanf("%d%d", &m, &n);
    sieve(n), p[1]=1;
    ll ans=0;
    for(int i=2;i<=n;i++) {
        if(lp[i]==i) {p[i]=i+1; continue;}
        int sum=1;
        int j=i, t=1;
        for(;j%lp[i]==0;t*=lp[i], sum+=t) j/=lp[i];
        p[i]=p[j]*sum;
    }
    for(int i=m;i<=n;i++) ans+=abs(p[i]-2*i);
    printf("%lld", ans);
    return 0;
}
/* stuff you should look for
    - int overflow, array bounds
    - special/edge cases (n=1?)
    - do smth instead of nothing and stay organized
    - WRITE STUFF DOWN
    - DONT JUST STICK ON ONE APPROACH
*/

Compilation message (stderr)

savrsen.cpp: In function 'int main()':
savrsen.cpp:48:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   48 |     scanf("%d%d", &m, &n);
      |     ~~~~~^~~~~~~~~~~~~~~~

• Subtask 1: 120 / 120