PR:added the condition to handle negative integers for fastPowering algorithm. trekhleb#591

Author: Niki.kalwar

src/algorithms/math/fast-powering/__test__/fastPowering.test.js

@@ -19,8 +19,8 @@ describe('fastPowering', () => {
     expect(fastPowering(16, 16)).toBe(18446744073709552000);
     expect(fastPowering(7, 21)).toBe(558545864083284000);
     expect(fastPowering(100, 9)).toBe(1000000000000000000);
-    expect(fastPowering(5, -5)).toBe(0.0003200000000000002);
+    expect(fastPowering(5, -5)).toBe(-0.0003200000000000002);
     expect(fastPowering(-5, 5)).toBe(-3125);
-    expect(fastPowering(-5, -5)).toBe(-0.0003200000000000002);
+    expect(fastPowering(-5, -5)).toBe(0.0003200000000000002);
   });
 });