move zeroes

Author: fishercoder1534

EASY/src/easy/MoveZeroes.java

@@ -0,0 +1,84 @@
+package easy;
+
+import utils.CommonUtils;
+
+/**283. Move Zeroes  QuestionEditorial Solution  My Submissions
+Total Accepted: 105705
+Total Submissions: 231420
+Difficulty: Easy
+Given an array nums, write a function to move all 0's to the end of it while maintaining the relative order of the non-zero elements.
+
+For example, given nums = [0, 1, 0, 3, 12], after calling your function, nums should be [1, 3, 12, 0, 0].
+
+Note:
+You must do this in-place without making a copy of the array.
+Minimize the total number of operations.*/
+public class MoveZeroes {
+    public void moveZeroes_Editorial_solution2(int[] nums){
+        //this solutoin is the most optimal since it minimizes the number of operations
+        //the idea is to swap the non-zero element to the first zero number position
+        for(int i = 0, j = 0; i < nums.length && j < nums.length; i++){
+            if(nums[i] != 0){
+                int temp = nums[i];
+                nums[i] = nums[j];
+                nums[j] = temp;
+                j++;
+            }
+        }
+    }
+    
+    public void moveZeroes_Editorial_solution1(int[] nums){
+        //keep the last non-zero index and keep overwriting it, then append zeroes to fill the end
+        int j = 0, i = 0;
+        for(; j < nums.length; j++){
+            if(nums[j] != 0){
+                nums[i++] = nums[j];
+            }
+        }
+        for(; i < nums.length; i++){
+            nums[i] = 0;
+        }
+    }
+    
+    //then I came up with this solution and got it AC'ed! Cheers!
+    //basically, find the next non-zero number and swap it with the current zero number
+    //Apparently it's not the most optimal, since this is basically an O(n^2) solution, then I turned to Editorial solutions
+    public void moveZeroes(int[] nums){
+        for(int i = 0; i < nums.length-1; i++){
+            if(nums[i] == 0){
+                int j = i+1;
+                while(j < nums.length && nums[j] == 0){
+                    j++;
+                }
+                if(j >= nums.length) return;
+                else {
+                    int temp = nums[j];
+                    nums[j] = nums[i];
+                    nums[i] = temp;
+                }
+            }
+        }
+    }
+    
+    //this approach won't preserve the relative order of the non-zero numbers
+    public void moveZeroes_1st_attempt(int[] nums) {
+        int i = 0, j = nums.length-1;
+        while(i < j){
+            if(nums[i] == 0){
+                int temp = nums[j];
+                nums[j] = nums[i];
+                nums[i] = temp;
+                j--;
+            } else {
+                i++;
+            }
+        }
+        CommonUtils.printArray(nums);
+    }
+    
+    public static void main(String...strings){
+        MoveZeroes test = new MoveZeroes();
+        int[] nums = new int[]{0,1,0,3,12};
+        test.moveZeroes_Editorial_solution2(nums);
+    }
+}