Reverse String II
给一个字符串和一个值k, 反转字符串, 规则是 每2k个, 反转前k个. 不够k个, 能反转多少反转多少. 不够2k个, 不转.
class Solution {
public String reverseStr(String s, int k) {
char[] ary = s.toCharArray();
for(int i = 0 ; i < ary.length; i += 2*k) {
swap(ary, i, Math.min(i + k - 1, ary.length-1));
}
return String.valueOf(ary);
}
private void swap(char[] ary, int i, int j) {
while(i < j) {
char t = ary[i];
ary[i] = ary[j];
ary[j] = t;
i++;
j--;
}
}
}