Write a function that takes a string as input and returns the string reversed. Example: Given s = "hello", return "olleh".
After the API changes
1 class Solution { 2 public void reverseString(char[] s) { 3 if (s == null || s.length == 0) return; 4 int l = 0, r = s.length - 1; 5 while (l < r) { 6 char temp = s[l]; 7 s[l] = s[r]; 8 s[r] = temp; 9 l ++; 10 r --; 11 } 12 } 13 }
注意没有append(0, s.charAt(i)), 是sb.insert(0, charAt(i));
1 public class Solution { 2 public String reverseString(String s) { 3 if (s == null) return null; 4 StringBuffer sb = new StringBuffer(); 5 for (int i=s.length()-1; i>=0; i--) { 6 sb.append(s.charAt(i)); 7 } 8 return sb.toString(); 9 } 10 }
1 public class Solution { 2 public String reverseString(String s) { 3 return new StringBuffer(s).reverse().toString(); 4 } 5 }