Add js file

ltp88 · ltp88 · commit 73451c342d52 · 2020-11-25T10:02:23.000-05:00
diff --git a/javascript/_1664.js b/javascript/_1664.js
@@ -0,0 +1,37 @@
+// Author: Phuong Lam
+
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var waysToMakeFair = function (nums) {
+  var total = 0
+
+  var lo = 0 // left odd
+  var le = 0 // left even
+  var ro = 0 // right odd
+  var re = 0 // right even
+
+  // when ignore 1 element => right odd mean i % 2 === 0
+  for (i = 0; i < nums.length; i++) {
+    if (i % 2 === 0) ro += nums[i]
+    else re += nums[i]
+  }
+
+  // remove position i, recalculate left - right even-odd
+  for (i = 0; i < nums.length; i++) {
+    // recalculate left
+    if (i > 0) {
+      if (i % 2 === 0) lo += nums[i - 1]
+      else le += nums[i - 1]
+    }
+
+    // recalculate right
+    if (i % 2 === 0) ro -= nums[i]
+    else re -= nums[i]
+
+    // calc total even & odd
+    if (lo + ro === le + re) total++
+  }
+  return total
+}
