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344. Reverse String

Description

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.

Solutions

• Java
• C++
• Python
• Go
• TypeScript
• Javascript
• RenderScript

• class Solution {
      public void reverseString(char[] s) {
          for (int i = 0, j = s.length - 1; i < j; ++i, --j) {
              char t = s[i];
              s[i] = s[j];
              s[j] = t;
          }
      }
  }
  

• class Solution {
  public:
      void reverseString(vector<char>& s) {
          for (int i = 0, j = s.size() - 1; i < j;) {
              swap(s[i++], s[j--]);
          }
      }
  };
  

• class Solution:
      def reverseString(self, s: List[str]) -> None:
          """
          Do not return anything, modify s in-place instead.
          """
          s[:] = s[::-1]
  
  #############
  
  class Solution:
      def reverseString(self, s: List[str]) -> None:
          i, j = 0, len(s) - 1
          while i < j:
              s[i], s[j] = s[j], s[i]
              i, j = i + 1, j - 1
  
  

• func reverseString(s []byte) {
  	for i, j := 0, len(s)-1; i < j; i, j = i+1, j-1 {
  		s[i], s[j] = s[j], s[i]
  	}
  }
  

• /**
   Do not return anything, modify s in-place instead.
   */
  function reverseString(s: string[]): void {
      for (let i = 0, j = s.length - 1; i < j; ++i, --j) {
          [s[i], s[j]] = [s[j], s[i]];
      }
  }
  
  

• /**
   * @param {character[]} s
   * @return {void} Do not return anything, modify s in-place instead.
   */
  var reverseString = function (s) {
      for (let i = 0, j = s.length - 1; i < j; ++i, --j) {
          [s[i], s[j]] = [s[j], s[i]];
      }
  };
  
  

• impl Solution {
      pub fn reverse_string(s: &mut Vec<char>) {
          let mut i = 0;
          let mut j = s.len() - 1;
          while i < j {
              s.swap(i, j);
              i += 1;
              j -= 1;
          }
      }
  }
  
  

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