ProjectEulerExercises/euler7.cpp at master · joaoreis28/ProjectEulerExercises · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;


ll upper_bound_primo(ll n)
{
    if(n < 6)
        return 100;
    return ceil(n * (log(n) + log(log(n))));
}

ll sieve(ll n)
{
    bool primo[n + 1];
    memset(primo, true, sizeof(primo));
    for(int p = 2; p*p <= n; p++)
        if(primo[p] == true)
            for(int i = p*p; i <=n; i+=p)
                primo[i] = false;

    ll cont = 0;
    for(int p = 2; p <= n; p++)
        if(primo[p] == true)
        {
            cont++;
            if(cont == 10001)
                return p;
        }

    return 0;
}


int main()
{
    cin.tie(0);
    ios_base::sync_with_stdio(0);
    ll upBound = upper_bound_primo(10001);

    cout << sieve(upBound)<< endl;
    return 0;
}