Codeforces GYM Battle of Brains

Solutions/2018 Battle Of Brains/F. Special Birthday Card.cpp

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+#include <bits/stdc++.h>
+using namespace std;
+#define int long long int
+#define pb push_back
+#define ub upper_bound
+#define lb lower_bound
+#define sz(s) (int)s.size()
+#define pii pair<int,int>
+#define piii pair< int,pair<int,int> >
+#define ff first
+#define ss second
+#define all(a) a.begin(),a.end()
+#define rall(v) v.rbegin(),v.rend()
+#define endl '\n'
+#define matrix vector<vector<int> >
+#define boost ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
+#define NAYAN freopen("input.txt","r",stdin);freopen("output.txt","w",stdout);
+#define N 1000005
+#define mod 1000000007
+#define inf 1e17
+
+int  a[N];
+vector <int> f[N];
+int mp[N];
+
+int cnt[N];
+void sieve()
+{
+    a[0]=1;
+    a[1]=1;
+    int i,j;
+    int n=sqrt(N)+2;
+    for(i=2;i<N;i++)
+    {
+        if(mp[i]==0)
+        {
+            for(j=i*i;j<N;j+=i)
+            {
+                if(mp[j]==0)
+                    mp[j]=i;
+            }
+        }
+    }
+    for(i=1;i<N;i++)
+    {
+        if(mp[i]==0)
+            mp[i]=i;
+    }
+}
+
+void factorize()
+{
+    int i;
+    for(i=1;i<N;i++)
+    {
+        //f[i].pb(1);
+        int n=i;
+        while(n!=1)
+        {
+            f[i].pb(mp[n]);
+            n/=mp[n];
+        }
+        int l=sz(f[i]);
+        if(l<=2)
+            cnt[i]=1;
+    }
+
+
+
+    for(i=1;i<N;i++)
+    {
+        cnt[i]=cnt[i]+cnt[i-1];
+    }
+}
+
+
+int32_t main()  
+{
+    boost
+    #ifndef ONLINE_JUDGE 
+    NAYAN
+    #endif
+    sieve();
+    factorize();
+    int t;
+    cin >> t;
+    int cn=1;
+    while(t--)
+    {
+        int n;
+        cin >> n;
+        int p,q;
+        p=cnt[n];
+        q=n;
+        int g=__gcd(p,q);
+        p/=g;
+        q/=g;
+        cout << "Case " << cn++ << ": " << p << "/" << q << endl;
+
+    }
+
+}