Sort array of 0,1 and 2s

Author: namitmalasi

SortArrayOf0s1sand2s.js

@@ -0,0 +1,64 @@
+//  Given an array arr[] consisting 0s, 1s and 2s.
+// The task is to write a function that sorts the given array.
+// The functions should put all 0s first, then all 1s and all 2s in last.
+
+// Approach 1()-->less Efficient
+function sortArrayOf0s1sand2s(arr) {
+  count0 = 0;
+  count1 = 0;
+  count2 = 0;
+
+  for (let i = 0; i < arr.length; i++) {
+    if (arr[i] === 0) {
+      count0++;
+    } else if (arr[i] === 1) {
+      count1++;
+    } else {
+      count2++;
+    }
+  }
+
+  let i = 0;
+
+  while (count0 > 0) {
+    arr[i++] = 0;
+    count0--;
+  }
+
+  while (count1 > 0) {
+    arr[i++] = 1;
+    count1--;
+  }
+
+  while (count2 > 0) {
+    arr[i++] = 2;
+    count2--;
+  }
+  return arr;
+}
+
+const arr = [2, 1, 0, 0, 1, 2, 0, 2, 1, 0];
+console.log(sortArrayOf0s1sand2s(arr));
+
+// Approach 2()-->More efficient
+function sortArrayOf0s1sand2s(arr) {
+  let left = 0;
+  let mid = 0;
+  let right = arr.length - 1;
+  while (mid <= right) {
+    if (arr[mid] === 0) {
+      [arr[mid], arr[left]] = [arr[left], arr[mid]];
+      left++;
+      mid++;
+    } else if (arr[mid] === 1) {
+      mid++;
+    } else {
+      [arr[mid], arr[right]] = [arr[right], arr[mid]];
+      right--;
+    }
+  }
+  return arr;
+}
+
+const arr = [2, 1, 0, 0, 1, 2, 0, 2, 1, 0];
+console.log(sortArrayOf0s1sand2s(arr));