Create 166-fraction-to-recurring-decimal.js

Author: everthis

166-fraction-to-recurring-decimal.js

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+/**
+ * @param {number} numerator
+ * @param {number} denominator
+ * @return {string}
+ */
+const fractionToDecimal = function (numerator, denominator) {
+  if (numerator === 0) return '0'
+  let s = ''
+  if (Math.sign(numerator) !== Math.sign(denominator)) s += '-'
+  let n = Math.abs(numerator)
+  const d = Math.abs(denominator)
+  s += Math.floor(n / d)
+  n %= d
+  if (n === 0) return s
+  s += '.'
+  const map = {}
+  while (n !== 0) {
+    map[n] = s.length
+    n *= 10
+    s += Math.floor(n / d)
+    n %= d
+    const i = map[n] // repeat starting index
+    if (i != null) return `${s.slice(0, i)}(${s.slice(i)})`
+  }
+  return s
+}