Separate the Digits in an Array
Method 1: Using String Conversion\n\njava\npublic int[] separateDigits(int[] nums) {\n    ArrayList<String> list = new ArrayList<>();\n    int i = 0;\n    while
# Method 1: Using String Conversion\n\n```java\npublic int[] separateDigits(int[] nums) {\n    ArrayList<String> list = new ArrayList<>();\n    int i = 0;\n    while (i < nums.length) {\n        String num = String.valueOf(nums[i++]); // Convert the number to a String\n        int l = 0;\n        while (l < num.length()) {\n            list.add(String.valueOf(num.charAt(l++))); // Add each digit as a separate String to the list\n        }\n    }\n\n    int[] ans = new int[list.size()];\n    for (i = 0; i < list.size(); i++) {\n        ans[i] = Integer.parseInt(list.get(i)); // Convert each String back to an integer\n    }\n    return ans; // Return the final array of digits\n}\n```\n\n# Explanation:\n1. **Conversion to String**:\n   - For each number in the input array `nums`, it\'s converted to a string using `String.valueOf(nums[i++])`.\n   - Each character in the string (which represents a digit) is added to an `ArrayList` as a separate string.\n\n2. **Reconstruction**:\n   - A new integer array `ans` is created, and each string from the `ArrayList` is converted back to an integer using `Integer.parseInt(list.get(i))` and placed into the `ans` array.\n\n# Use Case:\n- Input: `[123, 456]`\n- Process:\n  - Convert `123` to `"123"` and split into `"1"`, `"2"`, `"3"`\n  - Convert `456` to `"456"` and split into `"4"`, `"5"`, `"6"`\n  - Result: `[1, 2, 3, 4, 5, 6]`\n\n# Method 2: Using Only Integers and ArrayList\n\n```java\n// Method - 02: using only int and arrayList\npublic int[] separateDigits(int[] nums) {\n    ArrayList<Integer> list = new ArrayList<>();\n    int i = nums.length - 1;\n    while (i >= 0) {\n    int num = nums[i--];\n        while (num > 0) {\n        list.add(num % 10);\n        num = num / 10;\n        }\n    }\n    int[] ans = new int[list.size()];\n    int id = 0;\n    for (i = list.size() - 1; i >= 0; i--) {\n    ans[id++] = list.get(i);\n    }\n    return ans;\n// }\n```\n\n# Explanation:\n1. **Digit Extraction**:\n   - For each number in `nums`, digits are extracted from the last digit to the first using `num % 10`.\n   - The digit is added to the `ArrayList`, and then the last digit is removed using `num = num / 10`.\n\n2. **Reversing the Order**:\n   - Since digits are added in reverse order (from last to first), a second loop iterates over the `ArrayList` in reverse to place the digits in the correct order in the `ans` array.\n\n# Use Case:\n- Input: `[123, 456]`\n- Process:\n  - For `123`, extract `3`, `2`, `1`\n  - For `456`, extract `6`, `5`, `4`\n  - The digits are added in reverse order but then reversed again when populating the final array.\n  - Result: `[1, 2, 3, 4, 5, 6]`\n\n# Summary:\n- **Method 1** uses string manipulation, which can be straightforward but less efficient in terms of performance since it involves conversions between strings and integers.\n- **Method 2** (commented out) directly manipulates the digits as integers, potentially offering better performance but requiring careful handling of digit order.\n\nBoth methods ultimately produce the same result but with different approaches. If you don\'t make any changes to the code, you can choose between these methods based on your preference for either simplicity (Method 1) or efficiency (Method 2).
['Array', 'Simulation', 'Java']