Create fermats_little_theorem.cpp

Algorithms/Miscellaneous/C++/fermats_little_theorem.cpp

@@ -0,0 +1,54 @@
+
+#include <bits/stdc++.h>
+#define ll long long int
+// Compute (A^B)%mod, where A and B are can have <10^6 digits.
+using namespace std;
+ll power(ll a, ll b, ll mod)
+{
+    if (b == 0)
+        return 1;
+    ll ans = power(a, b / 2, mod);
+    ans %= mod;
+    ans = (ans * ans) % mod;
+    if ((b & 1) == 1)
+        return (ans * a) % mod;
+    return ans % mod;
+}
+ll stoi(string a, ll mod)
+{
+    ll ans = 0;
+    for (size_t i = 0; i < a.length(); i++)
+        ans = ((ans * 10) % mod + a[i] - '0') % mod;
+    return ans;
+}
+int main()
+{
+    ll n, m, mod = 1000000007;
+    ll t;
+    cin >> t;
+    string a, b;
+    while (t--)
+    {
+        cin >> a >> b;
+        n = stoi(a, mod);
+        m = stoi(b, mod - 1); // using fermats little theorem
+        cout << power(n, m, mod) << endl;
+    }
+    return 0;
+}
+
+/*
+Sample Input :
+5
+3 2
+4 5
+7 4
+34534985349875439875439875349875 93475349759384754395743975349573495
+34543987529435983745230948023948 3498573497543987543985743989120393097595572309482304
+Sample Output :
+9
+1024
+2401
+735851262
+985546465
+*/