Reverse Prefix of Word

1import java.util.Stack;
2
3class Solution {
4    // time O(n)
5    // space O(n)
6    public String reversePrefix(String word, char ch) {
7        Stack<Character> stack = new Stack<Character>();
8        boolean found = false;
9
10        for (int i = 0; i < word.length(); i++) {
11            stack.push(word.charAt(i));
12
13            if (word.charAt(i) == ch) {
14                found = true;
15                break;
16            }
17        }
18
19        if (!found) {
20            return word;
21        }
22
23        StringBuilder sb = new StringBuilder(word);
24        int j = 0;
25        while (!stack.isEmpty()) {
26            sb.setCharAt(j, stack.pop());
27            j++;
28        }
29
30        return sb.toString();
31    }
32}