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Commit af85cd9

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author
Sandy
authored
Merge pull request #6 from openset/develop
Add: remove_element
2 parents 8c94d7b + 0a3486a commit af85cd9

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‎solution/remove-element/README.md

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## 27. Remove Element
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Given an array nums and a value val, remove all instances of that value `in-place` and return the new length.
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Do not allocate extra space for another array, you must do this by `modifying the input array` `in-place` with O(1) extra memory.
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The order of elements can be changed. It doesn't matter what you leave beyond the new length.
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**Example 1:**
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```
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Given nums = [3,2,2,3], val = 3,
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Your function should return length = 2, with the first two elements of nums being 2.
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It doesn't matter what you leave beyond the returned length.
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```
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**Example 2:**
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```
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Given nums = [0,1,2,2,3,0,4,2], val = 2,
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Your function should return length = 5, with the first five elements of nums containing 0, 1, 3, 0, and 4.
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Note that the order of those five elements can be arbitrary.
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It doesn't matter what values are set beyond the returned length.
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```
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**Clarification:**
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Confused why the returned value is an integer but your answer is an array?
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Note that the input array is passed in by reference, which means modification to the input array will be known to the caller as well.
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Internally you can think of this:
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```
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// nums is passed in by reference. (i.e., without making a copy)
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int len = removeElement(nums, val);
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// any modification to nums in your function would be known by the caller.
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// using the length returned by your function, it prints the first len elements.
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for (int i = 0; i < len; i++) {
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print(nums[i]);
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}
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```
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package remove_element
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func removeElement(nums []int, val int) int {
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l := 0
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for _, v := range nums {
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if v != val {
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nums[l] = v
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l++
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}
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}
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return l
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}
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package remove_element
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import (
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"testing"
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)
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type caseType struct {
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input []int
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val int
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expected []int
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}
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func TestRemoveElement(t *testing.T) {
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tests := [...]caseType{
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{
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input: []int{3, 2, 2, 3},
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val: 3,
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expected: []int{2, 2},
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},
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{
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input: []int{0, 1, 2, 2, 3, 0, 4, 2},
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val: 2,
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expected: []int{0, 1, 3, 0, 4},
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},
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{
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input: []int{1, 2, 3, 4, 5},
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val: 6,
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expected: []int{1, 2, 3, 4, 5},
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},
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{
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input: []int{1, 2, 2, 3, 3, 3, 4, 4, 4, 4},
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val: 4,
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expected: []int{1, 2, 2, 3, 3, 3},
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},
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{
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input: nil,
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val: 1,
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expected: nil,
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},
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}
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for _, tc := range tests {
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nums := make([]int, len(tc.input))
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copy(nums, tc.input)
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l := removeElement(nums, tc.val)
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output := nums[:l]
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if l != len(tc.expected) {
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t.Fatalf("input: %v, output: %v, expected: %v", tc.input, output, tc.expected)
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}
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for k, v := range tc.expected {
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if output[k] != v {
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t.Fatalf("input: %v, output: %v, expected: %v", tc.input, output, tc.expected)
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}
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}
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}
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}

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