Helper math library added for bigint operations

https://golb.hplar.ch/2018/09/javascript-bigint.html#math

Author: Gonzalo Diaz

src/hackerrank/lib/BigIntMath.ts

@@ -0,0 +1,81 @@
+/* istanbul ignore file */
+
+export class BigIntMath {
+  static max(...values: bigint[]): bigint | null {
+    if (values.length === 0) {
+      return null;
+    }
+
+    if (values.length === 1) {
+      return values[0];
+    }
+
+    let max = values[0];
+    for (let i = 1; i < values.length; i++) {
+      if (values[i] > max) {
+        max = values[i];
+      }
+    }
+    return max;
+  }
+
+  static min(...values: bigint[]): bigint | null {
+    if (values.length === 0) {
+      return null;
+    }
+
+    if (values.length === 1) {
+      return values[0];
+    }
+
+    let min = values[0];
+    for (let i = 1; i < values.length; i++) {
+      if (values[i] < min) {
+        min = values[i];
+      }
+    }
+    return min;
+  }
+
+  static sign(value: bigint): bigint {
+    if (value > 0n) {
+      return 1n;
+    }
+    if (value < 0n) {
+      return -1n;
+    }
+    return 0n;
+  }
+
+  static abs(value: bigint): bigint {
+    if (this.sign(value) === -1n) {
+      return -value;
+    }
+    return value;
+  }
+
+  // https://stackoverflow.com/questions/53683995/javascript-big-integer-square-root/58863398#58863398
+  static rootNth(value: bigint, k = 2n): bigint {
+    if (value < 0n) {
+      throw Error('negative number is not supported');
+    }
+
+    let o = 0n;
+    let x = value;
+    let limit = 100;
+
+    while (x ** k !== k && x !== o && limit > 0) {
+      limit -= 1;
+      o = x;
+      x = ((k - 1n) * x + value / x ** (k - 1n)) / k;
+    }
+
+    return x;
+  }
+
+  static sqrt(value: bigint): bigint {
+    return BigIntMath.rootNth(value);
+  }
+}
+
+export default { BigIntMath };