0027: Remove Element (#3)

Author: golevy

0027-Remove_Element/main.ts

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+// let nums = [3, 2, 2, 3],
+//   val = 3,
+//   expectedNums = [2, 2];
+let nums = [0, 1, 2, 2, 3, 0, 4, 2],
+  val = 2,
+  expectedNums = [0, 1, 3, 0, 4];
+
+function removeElement(nums: number[], val: number): number {
+  let slowIndex = 0;
+  for (let fastIndex = 0; fastIndex < nums.length; fastIndex++) {
+    if (nums[fastIndex] !== val) {
+      nums[slowIndex] = nums[fastIndex];
+      slowIndex++;
+    }
+  }
+  return slowIndex;
+}
+
+let k = removeElement(nums, val);
+
+console.assert(k === expectedNums.length, "Length mismatch");
+
+nums.slice(0, k).sort((a, b) => a - b);
+
+for (let i = 0; i < k; i++) {
+  console.assert(nums[i] === expectedNums[i], `Element mismatch at index ${i}`);
+}
+
+console.log(k);
+console.log(nums);

0027-Remove_Element/readme.md

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+# 27. Remove Element
+
+Given an integer array `nums` and an integer `val`, remove all occurrences of `val` in `nums` [in-place](https://en.wikipedia.org/wiki/In-place_algorithm). The order of the elements may be changed. Then return the number of elements in `nums` which are not equal to `val`.
+
+Consider the number of elements in `nums` which are not equal to `val` be `k`, to get accepted, you need to do the following things:
+
+- Change the array `nums` such that the first `k` elements of `nums` contain the elements which are not equal to `val`. The remaining elements of `nums` are not important as well as the size of `nums`.
+- Return `k`.
+
+### Custom Judge:
+
+The judge will test your solution with the following code:
+
+```
+int[] nums = [...]; // Input array
+int val = ...; // Value to remove
+int[] expectedNums = [...]; // The expected answer with correct length.
+// It is sorted with no values equaling val.
+
+int k = removeElement(nums, val); // Calls your implementation
+
+assert k == expectedNums.length;
+sort(nums, 0, k); // Sort the first k elements of nums
+for (int i = 0; i < actualLength; i++) {
+assert nums[i] == expectedNums[i];
+}
+```
+
+If all assertions pass, then your solution will be accepted.
+
+### Example 1:
+
+> <span style="color: white;">Input: </span>nums = [3, 2, 2, 3], val = 3<br>
+> <span style="color: white;">Output: </span>2, nums = [2, 2, _, _]<br>
+> <span style="color: white;">Explanation: </span>Your function should return k = 2, with the first two elements of nums being 2.<br>
+> It does not matter what you leave beyond the returned k (hence they are underscores).
+
+### Example 2:
+
+> <span style="color: white;">Input: </span>nums = [0, 1, 2, 2, 3, 0, 4, 2], val = 2<br>
+> <span style="color: white;">Output: </span>5, nums = [0, 1, 4, 0, 3, _, _, _]<br>
+> <span style="color: white;">Explanation: </span>Your function should return k = 5, with the first five elements of nums containing 0, 0, 1, 3, and 4.<br>
+Note that the five elements can be returned in any order.<br>
+It does not matter what you leave beyond the returned k (hence they are underscores).
+
+### Constraints:
+
+- `0 <= nums.length <= 100`
+- `0 <= nums[i] <= 50`
+- `0 <= val <= 100`