[LeetCode] Problem 344 - Reverse String

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Write a function that reverses a string. The input string is given as an array of characters char[].

Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.

You may assume all the characters consist of printable ascii characters.

Example

No.1

Input: [“h”,”e”,”l”,”l”,”o”]

Output: [“o”,”l”,”l”,”e”,”h”]

No.2

Input: [“H”,”a”,”n”,”n”,”a”,”h”]

Output: [“h”,”a”,”n”,”n”,”a”,”H”]

Code

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public void reverseString(char[] s) {
    int start = 0;
    int end = s.length - 1;

    while (start < end) {
        char temp = s[end];
        s[end] = s[start];
        s[start] = temp;

        start++;
        end--;
    }
}