From 4d44bb16d2b605a3bae1a12eb3fe5806893b9ebd Mon Sep 17 00:00:00 2001
From: Gaurang Telang <58006887+gstelang@users.noreply.github.com>
Date: Sat, 24 Jul 2021 09:59:08 -0700
Subject: [PATCH] Create array-equal-split-index.js

---
 array-equal-split-index.js | 41 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 array-equal-split-index.js

diff --git a/array-equal-split-index.js b/array-equal-split-index.js
new file mode 100644
index 0000000..a70f2a3
--- /dev/null
+++ b/array-equal-split-index.js
@@ -0,0 +1,41 @@
+
+const findIndex = (arr) => {
+  if (arr.length === 1 || arr.length === 2) {
+    console.log(`no index for arr with length ${arr.length}`);
+    return;
+  }
+
+  const sum = arr.reduce((acc, val) => acc + val, 0);
+
+  let leftSum = 0,
+    rightSum = sum - arr[0],
+    index = 1,
+    missingIndex = 0;
+
+  while (index < arr.length) {
+
+    // console.log(`${index} => ${leftSum}, ${rightSum}`);
+    if (leftSum === rightSum) {
+      // console.log('found index');
+      missingIndex = index - 1;
+      break;
+    }
+    rightSum = rightSum - arr[index];
+    leftSum = leftSum + arr[index - 1];
+    index = index + 1;
+  }
+
+
+  if (missingIndex === 0) {
+    console.log('no such index');
+  } else {
+    console.log(missingIndex);
+  }
+};
+
+findIndex([1]);
+findIndex([1, 2]);
+findIndex([1, 2, 3]); // no index
+findIndex([2, 2, 2]); // index at 1
+findIndex([1, 2, 3, 4, 10, 9, 5, 5, 4, 6]); // index at 5
+