Create 927-three-equal-parts.js

Author: everthis

927-three-equal-parts.js

@@ -0,0 +1,39 @@
+/**
+ * @param {number[]} A
+ * @return {number[]}
+ */
+const threeEqualParts = function (A) {
+  let countNumberOfOnes = 0
+  for (let c of A) if (c === 1) countNumberOfOnes++
+  if (countNumberOfOnes === 0) return [0, A.length - 1]
+  if (countNumberOfOnes % 3 != 0) return [-1, -1]
+  const k = countNumberOfOnes / 3
+  let i
+  // find the first 1 in the array
+  for (i = 0; i < A.length; i++) if (A[i] == 1) break
+  let start = i
+  // find (k+1)th 1 in the array
+  let count1 = 0
+  for (i = 0; i < A.length; i++) {
+    if (A[i] == 1) count1++
+    if (count1 == k + 1) break
+  }
+  let mid = i
+  //find (2*k +1)th 1 in the array
+  count1 = 0
+  for (i = 0; i < A.length; i++) {
+    if (A[i] === 1) count1++
+    if (count1 === 2 * k + 1) break
+  }
+  let end = i
+  // Match all values till the end of the array
+  while (end < A.length && A[start] === A[mid] && A[mid] === A[end]) {
+    start++
+    mid++
+    end++
+  }
+  // Return appropriate values if all the values have matched till the end
+  if (end == A.length) return [start - 1, mid]
+  // otherwise, no such indices found
+  return [-1, -1]
+}