add prime, change typedef to using

Author: atcoder-live

prime.cpp

@@ -0,0 +1,39 @@
+// Sieve of Eratosthenes
+// https://youtu.be/UTVg7wzMWQc?t=2774
+struct Sieve {
+  int n;
+  vector<int> f, primes;
+  Sieve(int n=1):n(n), f(n+1) {
+    f[0] = f[1] = -1;
+    for (ll i = 2; i <= n; ++i) {
+      if (f[i]) continue;
+      primes.push_back(i);
+      f[i] = i;
+      for (ll j = i*i; j <= n; j += i) {
+        if (!f[j]) f[j] = i;
+      }
+    }
+  }
+  bool isPrime(int x) { return f[x] == x;}
+  vector<int> factorList(int x) {
+    vector<int> res;
+    while (x != 1) {
+      res.push_back(f[x]);
+      x /= f[x];
+    }
+    return res;
+  }
+  vector<P> factor(int x) {
+    vector<int> fl = factorList(x);
+    if (fl.size() == 0) return {};
+    vector<P> res(1, P(fl[0], 0));
+    for (int p : fl) {
+      if (res.back().first == p) {
+        res.back().second++;
+      } else {
+        res.emplace_back(p, 1);
+      }
+    }
+    return res;
+  }
+};

template.cpp

@@ -1,7 +1,8 @@
 #include <bits/stdc++.h>
 #define rep(i,n) for (int i = 0; i < (n); ++i)
 using namespace std;
-typedef long long ll;
+using ll = long long;
+using P = pair<int,int>;
 
 int main() {
   return 0;