package jjn.carl.string;
import java.util.Arrays;
/** * @author Jjn * @since 2023/7/5 11:39 */public class LeetCode344 {    public void reverseString(char[] s) {        int left = 0, right = s.length - 1;        while (left < right) {            char temp = s[left];            s[left] = s[right];            s[right] = temp;            left++;            right--;        }    }        public static void main(String[] args) {        String s = "aabbcc";        char[] input = s.toCharArray();        new LeetCode344().reverseString(input);        System.out.println("input = " + Arrays.toString(input));    }}

package jjn.carl.string;
/** * @author Jjn * @since 2023/7/5 16:41 */public class LeetCode541 {      // 自己写的比较笨的方法，运行需要4ms，只能超过百分之十几的    public String reverseStr(String s, int k) {        StringBuilder stringBuilder = new StringBuilder();        int left = 0, right = 0;        while (left < s.length() && right < s.length()) {            right = left + k - 1;            for (int i = Math.min(right, s.length() - 1); i >= left; i--) {                stringBuilder.append(s.charAt(i));            }            left = right + 1;            right = left + k - 1;            for (int i = left; i <= Math.min(right, s.length() - 1); i++) {                stringBuilder.append(s.charAt(i));            }            left = right + 1;        }        return stringBuilder.toString();    }        public static void main(String[] args) {        // 如果剩余字符少于 k 个，则将剩余字符全部反转。        // 如果剩余字符小于 2k 但大于或等于 k 个，则反转前 k 个字符，其余字符保持原样。        // bacdfeg        System.out.println("new LeetCode541().reverseStr(\"abcdefg\", 2) = " + new LeetCode541().reverseStr("abcdefg", 2));        // bacd        System.out.println("new LeetCode541().reverseStr(\"abcd\", 2) = " + new LeetCode541().reverseStr("abcd", 2));    }}

package jjn.carl.string;
/** * @author Jjn * @since 2023/7/5 16:41 */public class LeetCode541_2 {    public String reverseStr(String s, int k) {        char[] chars = s.toCharArray();        for (int i = 0; i < s.length(); i = i + 2 * k) {            int end = Math.min(i + k - 1, s.length() - 1);            reverse(chars, i, end);        }        return new String(chars);    }        private void reverse(char[] chars, int start, int end) {        while (start < end) {            char temp = chars[start];            chars[start] = chars[end];            chars[end] = temp;            start++;            end--;        }    }        public static void main(String[] args) {        // 如果剩余字符少于 k 个，则将剩余字符全部反转。        // 如果剩余字符小于 2k 但大于或等于 k 个，则反转前 k 个字符，其余字符保持原样。        // bacdfeg        System.out.println("new LeetCode541().reverseStr(\"abcdefg\", 2) = " + new LeetCode541_2().reverseStr("abcdefg", 2));        // bacd        System.out.println("new LeetCode541().reverseStr(\"abcd\", 2) = " + new LeetCode541_2().reverseStr("abcd", 2));    }}

package jjn.carl.string;
/** * @author Jiang Jining * @since 2023-07-05 23:31 */public class Offer5 {    public String replaceSpace(String s) {        StringBuilder sb = new StringBuilder();        for (char c : s.toCharArray()) {            if (c == ' ') {                sb.append("%20");            } else {                sb.append(c);            }        }        return sb.toString();    }        public static void main(String[] args) {        String replacedSpace = new Offer5().replaceSpace("We are happy.");        System.out.println("replacedSpace = " + replacedSpace);    }}

package jjn.carl.string;
/** * @author Jiang Jining * @since 2023-07-05 23:33 */public class LeetCode151 {    public String reverseWords(String s) {        // 每个单词的开始和结束索引（左闭右开）        int start, end;        StringBuilder sb = new StringBuilder();        for (int i = s.length() - 1; i >= 0; i--) {            if (s.charAt(i) == ' ') {                //跳过空格                continue;            }            //找到结束索引            end = i + 1;            while (i >= 0 && s.charAt(i) != ' ') {                //跳过空格                i--;            }            //找到开始索引            start = i + 1;            for (int j = start; j < end; j++) {                //将每个单词按开始结束索引赋值到StringBuilder                sb.append(s.charAt(j));            }            //加上单词间的空格            sb.append(' ');        }        //删掉最后一个多余的空格        sb.deleteCharAt(sb.length() - 1);        return sb.toString();    }        public static void main(String[] args) {        System.out.println("new LeetCode151().reverseWords(\"the sky is blue\") = " + new LeetCode151().reverseWords("the sky is blue"));        System.out.println("new LeetCode151().reverseWords(\"  hello world  \") = " + new LeetCode151().reverseWords("  hello world  "));        System.out.println("new LeetCode151().reverseWords(\"a good   example\") = " + new LeetCode151().reverseWords("a good   example"));    }}