leetcode

Author: ayoubzulfiqar

README.md

@@ -131,6 +131,7 @@ This repo contain leetcode solution using DART and GO programming language. Most
 - [**338.** Counting Bits](CountingBits/counting_bits.dart)
 - [**374.** Guess Number Higher or Lower](GuessNumberHigherOrLower/guess_number_higher_or_lower.dart)
 - [**342.** Power of Four](PowerOfFour/power_of_four.dart)
+- [**344.** Reverse String](ReverseString/reverse_string.dart)
 
 ## Reach me via
 

ReverseString/reverse_string.dart

@@ -0,0 +1,103 @@
+/*
+
+
+
+-* 344. Reverse String *-
+
+
+Write a function that reverses a string. The input string is given as an array of characters s.
+
+You must do this by modifying the input array in-place with O(1) extra memory.
+
+
+
+Example 1:
+
+Input: s = ["h","e","l","l","o"]
+Output: ["o","l","l","e","h"]
+Example 2:
+
+Input: s = ["H","a","n","n","a","h"]
+Output: ["h","a","n","n","a","H"]
+
+
+Constraints:
+
+1 <= s.length <= 105
+s[i] is a printable ascii character.
+
+*/
+
+class A {
+  void solve(List<String> s, int left, int right) {
+    if (left >= right) return;
+    String temp = s[left];
+    s[left] = s[right];
+    s[right] = temp;
+    solve(s, ++left, --right);
+  }
+
+  void reverseString(List<String> s) {
+    int left = 0;
+    int right = s.length - 1;
+    solve(s, left, right);
+  }
+}
+
+class B {
+  void reverseString(List<String> s) {
+    int left = 0, right = s.length - 1;
+    while (left < right) {
+      String temp = s[right];
+      s[right--] = s[left];
+      s[left++] = temp;
+    }
+  }
+}
+
+class C {
+  void reverseString(List<String> s) {
+    // Declare integer variable and initialize them
+    int i = 0, j = 0, k = 0;
+    // Initialize stack
+    List<String> stack = [];
+    // Initialize string
+    String str = s.toString();
+    // Push all elements into the stack
+    for (i = 0; i < str.length; i++) {
+      stack.add(s[i]);
+    }
+    // Initialize another array
+    List<String> array = List.filled(s.length, "");
+    // Pop elements from stack
+    while (stack.length > 0) {
+      s[j++] = stack.removeLast(); //Increment j accordingly
+    }
+    // Fill the other array with popped elements from stack
+    for (k = 0; k < str.length; k++) {
+      array[k] = str[k];
+    }
+  }
+}
+
+class D {
+  void reverseString(List<String> s) {
+    //create a stack
+    List<String> st = [];
+    //loop through the string, to add all the string elements in stack
+    for (int i = 0; i < s.length; i++) {
+      //create a variable to add the values
+      String ch = s[i];
+      st.add(ch);
+    }
+    //empty the original string
+    s.clear();
+    //add the stack elements to the string
+    while (!st.isEmpty) {
+      String ch = st.first;
+      //reversed
+      s.add(ch);
+      st.removeLast();
+    }
+  }
+}

ReverseString/reverse_string.go

@@ -0,0 +1,10 @@
+package main
+
+func reverseString(s []byte) {
+	l, r := 0, len(s)-1
+	for i := 0; i < len(s)/2; i++ {
+		l = i
+		r = len(s) - (i + 1)
+		s[l], s[r] = s[r], s[l]
+	}
+}

ReverseString/reverse_string.md

@@ -0,0 +1,62 @@
+# 🔥 Reverse String 🔥 || 3 Approaches || Simple Fast and Easy || with Explanation
+
+## Solution - 1
+
+```dart
+class Solution {
+  void solve(List<String> s, int left, int right) {
+    if (left >= right) return;
+    String temp = s[left];
+    s[left] = s[right];
+    s[right] = temp;
+    solve(s, ++left, --right);
+  }
+
+  void reverseString(List<String> s) {
+    int left = 0;
+    int right = s.length - 1;
+    solve(s, left, right);
+  }
+}
+```
+
+## Solution - 2
+
+```dart
+class Solution {
+  void reverseString(List<String> s) {
+    int left = 0, right = s.length - 1;
+    while (left < right) {
+      String temp = s[right];
+      s[right--] = s[left];
+      s[left++] = temp;
+    }
+  }
+}
+```
+
+## Solution - 3
+
+```dart
+class Solution {
+  void reverseString(List<String> s) {
+    //create a stack
+    List<String> st = [];
+    //loop through the string, to add all the string elements in stack
+    for (int i = 0; i < s.length; i++) {
+      //create a variable to add the values
+      String ch = s[i];
+      st.add(ch);
+    }
+    //empty the original string
+    s.clear();
+    //add the stack elements to the string
+    while (!st.isEmpty) {
+      String ch = st.first;
+      //reversed
+      s.add(ch);
+      st.removeLast();
+    }
+  }
+}
+```