344 reverse string resolved. (#16)

zwfang · web-flow · commit 47caff47e97b · 2018-12-26T11:28:43.000+08:00
diff --git a/README.md b/README.md
@@ -34,6 +34,7 @@ continually updating 😃.
 * [67. Add Binary](./src/0067_add_binary/add_binary.go)&nbsp;&nbsp;&nbsp;*`brute force`*
 * [76. Minimum Window Substring](./src/0076_minimum_window_substring/minimum_window_substring.go) &nbsp;&nbsp;&nbsp;*`sliding window`*
 * [125. Valid Palindrome](./src/0125_valid_palindrome/valid_palindrome.go)&nbsp;&nbsp;&nbsp;*`string;`*&nbsp;&nbsp;*`double index`*
+* [344. Reverse String](0344_reverse_string/reverse_string.go)&nbsp;&nbsp;&nbsp;*`string;`*&nbsp;&nbsp;*`double index`*
 * [438. Find All Anagrams in a String](./src/0438_all_anagrams_in_a_string/all_anagrams_in_a_string.go)&nbsp;&nbsp;&nbsp;*`sliding window`*
 
 ### Linked List
diff --git a/src/0344_reverse_string/reverse_string.go b/src/0344_reverse_string/reverse_string.go
@@ -0,0 +1,41 @@
+/*
+344. Reverse String
+https://leetcode.com/problems/reverse-string/
+
+Write a function that takes a string as input and returns the string reversed.
+*/
+// time: 2018-12-26
+
+package reversestring
+
+// double index
+// time complexity: O(n)
+// space complexity: O(1)
+func reverseString(s string) string {
+	var (
+		l int
+		r = len(s) - 1
+	)
+
+	for r >= l {
+		charL := s[l]
+		charR := s[r]
+		s = s[:r] + string(charL) + s[r+1:]
+		s = s[:l] + string(charR) + s[l+1:]
+		r--
+		l++
+	}
+	return s
+}
+
+// double index
+// time complexity: O(n)
+// space complexity: O(n)
+func reverseString1(s string) string {
+	sLen := len(s)
+	runes := []rune(s)
+	for i := 0; i < sLen/2; i++ {
+		runes[i], runes[sLen-i-1] = runes[sLen-i-1], runes[i]
+	}
+	return string(runes)
+}
diff --git a/src/0344_reverse_string/reverse_string_test.go b/src/0344_reverse_string/reverse_string_test.go
@@ -0,0 +1,45 @@
+package reversestring
+
+import "testing"
+
+func TestReverseString(t *testing.T) {
+	testCases := []string{
+		"hello",
+		"A man, a plan, a canal: Panama",
+		"",
+		"ab",
+	}
+	expected := []string{
+		"olleh",
+		"amanaP :lanac a ,nalp a ,nam A",
+		"",
+		"ba",
+	}
+
+	for index, data := range testCases {
+		if res := reverseString(data); res != expected[index] {
+			t.Errorf("expected %s, got %s", expected[index], res)
+		}
+	}
+}
+
+func TestReverseString1(t *testing.T) {
+	testCases := []string{
+		"hello",
+		"A man, a plan, a canal: Panama",
+		"",
+		"ab",
+	}
+	expected := []string{
+		"olleh",
+		"amanaP :lanac a ,nalp a ,nam A",
+		"",
+		"ba",
+	}
+
+	for index, data := range testCases {
+		if res := reverseString1(data); res != expected[index] {
+			t.Errorf("expected %s, got %s", expected[index], res)
+		}
+	}
+}
diff --git a/src/README.md b/src/README.md
@@ -40,6 +40,7 @@
 |0283|[Move Zeroes(solution1)](./0283_move_zeroes/move_zeroes.go) <br/>  [Move Zeroes(solution2)](./0283_move_zeroes/move_zeroes2.go)|Easy|*`array`*|
 |0300|[Longest Increasing Subsequence](./0300_longest_increasing_subsequence/lis.go)|Medium|*`dp`*|
 |0343|[Integer Break](./0343_integer_break/integer_break.go)|Medium|*`recursion;`* *`memory search;`* *`dynamic programming`*|
+|0344|[344. Reverse String](0344_reverse_string/reverse_string.go)|Easy|*`double index`*|
 |0349|[Intersection of Two Arrays](./0349_intersection_of_2_arrays/intersection_of_two_arrays.go)|Easy|*`set`*|
 |0350| [Intersection of Two Arrays II](./0350_intersection_of_two_arrays2/intersection_of_two_arrays2.go)|Easy|*`map`*|
 |0376|[Wiggle Subsequence](./0376_wiggle_subsequence/wiggle_subsequence.go)|Medium|*`dp`*|
