【双指针+字符串】字符串变形

求解代码

public String trans(String s, int n) {
        if (s == null || s.length() == 0) {
            return s;
        }
        char[] str = s.toCharArray();
        reverse(str, 0, str.length - 1);
        int i = 0, j = 0;
        while (i < str.length) {
            j = i;
            while (j < str.length && str[j] != ' ') {
                if (str[j] >= 'a' && str[j] <= 'z') {
                    str[j] = (char) (str[j] - 'a' + 'A');
                } else {
                    str[j] = (char) (str[j] - 'A' + 'a');
                }
                j++;
            }
            reverse(str, i, j - 1);
            i = j + 1;
        }
        return new String(str);
    }

    public void reverse(char[] arr, int start, int end) {
        int i = start;
        int j = end;
        while (i < j) {
            char c = arr[i];
            arr[i] = arr[j];
            arr[j] = c;
            i++;
            j--;
        }
    }

小贴士

代码思路大概是：

整体反转➡️单词遍历➡️大小写互换➕局部反转