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125 valid palindrome solved. #15

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zwfang merged 1 commit into master from valid-palindrome
Dec 26, 2018
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1 change: 1 addition & 0 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,7 @@ continually updating 😃.
* [20. Valid Parentheses](./src/0020_valid_parentheses/valid_parentheses.go)   *`stack`*
* [67. Add Binary](./src/0067_add_binary/add_binary.go)   *`brute force`*
* [76. Minimum Window Substring](./src/0076_minimum_window_substring/minimum_window_substring.go)    *`sliding window`*
* [125. Valid Palindrome](./src/0125_valid_palindrome/valid_palindrome.go)   *`string;`*  *`double index`*
* [438. Find All Anagrams in a String](./src/0438_all_anagrams_in_a_string/all_anagrams_in_a_string.go)   *`sliding window`*

### Linked List
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45 changes: 45 additions & 0 deletions src/0125_valid_palindrome/valid_palindrome.go
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@@ -0,0 +1,45 @@
/*
125. Valid Palindrome
https://leetcode.com/problems/valid-palindrome/

Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.

Note: For the purpose of this problem, we define empty string as valid palindrome.
*/

// time: 2018年12月26日

package validpalindrome

// double index
// time complexity: O(n)
// space complexity: O(n)
func isPalindrome(s string) bool {
chars := make([]uint8, 0)

for i := 0; i < len(s); i++ {
if s[i] >= 65 && s[i] <= 90 {
chars = append(chars, s[i])
}
if s[i] >= 97 && s[i] <= 122 {
chars = append(chars, s[i]-32)
}
if s[i] >= 48 && s[i] <= 57 {
chars = append(chars, s[i])
}
}

var (
l int
r = len(chars) - 1
)

for r >= l {
if chars[r] != chars[l] {
return false
}
r--
l++
}
return true
}
20 changes: 20 additions & 0 deletions src/0125_valid_palindrome/valid_palindrome_test.go
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package validpalindrome

import "testing"

func TestIsPalindrome(t *testing.T) {
testCases := []string{
"A man, a plan, a canal: Panama",
"race a car",
"0P",
"",
}

expected := []bool{true, false, false, true}

for index, data := range testCases {
if res := isPalindrome(data); res != expected[index] {
t.Errorf("expected %t, got %t", expected[index], res)
}
}
}
1 change: 1 addition & 0 deletions src/README.md
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Expand Up @@ -31,6 +31,7 @@
|0111|[Minimum Depth of Binary Tree](./0111_minimum_depth_of_binary_tree/minimum_depth_of_binary_tree.go)|Easy|*`binary tree`*|
|0112|[Path Sum](./0112_path_sum/path_sum.go)|Easy|*`binary tree`*|
|0120|[Triangle](./0120_triangle/triangle.go)|Medium|*`dynamic programming;`* *` dfs`*|
|0125|[Valid Palindrome](0125_valid_palindrome/valid_palindrome.go)|Easy||
|0167|[Two Sum II - Input array is sorted](./0167_two_sum2/two_sum2.go)|Easy|*`对撞指针(双索引)`*|
|0198|[House Robber](./0198_house_robber/house_robber.go)|Easy|*`memory search;`* *`dynamic programming`*|
|0209|[Minimum Size Subarray Sum](./0209_minimum_size_subarray_sum/minimum_size_subarray_sum.go)|Medium|*`sliding window`*|
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