Create 1020-partition-array-into-three-parts-with-equal-sum.js

Author: everthis

1020-partition-array-into-three-parts-with-equal-sum.js

@@ -0,0 +1,31 @@
+/**
+ * @param {number[]} A
+ * @return {boolean}
+ */
+const canThreePartsEqualSum = function(A) {
+  let lo = 0
+  let hi = A.length - 1
+  let lsum = 0
+  let hsum = 0
+  const sum = A.reduce((ac, el) => ac + el, 0)
+  if(sum % 3 !== 0) return false
+  const target = sum / 3
+
+  while(lo < hi && lsum !== target) {
+    lsum += A[lo]
+    lo++
+  }
+  if(lsum !== target) return false
+  while(lo < hi && hsum !== target) {
+    hsum += A[hi]
+    hi--
+  }
+  if(hsum !== target) return false
+
+  let msum = 0
+  for(let i = lo; i <= hi; i++) {
+    msum += A[i]
+  }
+  if(msum !== target) return false
+  return true
+};