【剑指offer第二版】面试题5：替换空格（java）

柔情只为你懂 2022-02-28 03:46 306阅读 0赞

转载自[https://blog.csdn.net/weixin\_37672169/article/details/79979710][https_blog.csdn.net_weixin_37672169_article_details_79979710]

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题目：请实现一个函数，把字符串中的每个空格替换成“%20”。例如输入“We are happy”，则输出”We%20are%20happy”.

/**
     * 将字符串中的空格替换为%20
     */
    public class Solution{
    
        /**
         * 使用StringBuilder的方法
         * @param inputStr 输入的字符串
         * @return
         */
        public static String replaceSpace(String inputStr) {
            if (inputStr == null || inputStr.length() == 0) {
                return null;
            }
            StringBuilder strBuilder = new StringBuilder();
    
            for (int i = 0; i < inputStr.length(); i++) {
                if (inputStr.charAt(i) == ' ') {
                    strBuilder.append("%20");
                } else {
                    strBuilder.append(inputStr.charAt(i));
                }
            }
            return strBuilder.toString();
        }
    
        public static void main(String args[]) {
            /**
             * 测试用例
             */
            String str1 = "We are happy.";
            String str2 = " Wearehappy.";
            String str3 = "Wearehappy. ";
            String str4 = "We   are   happy  .";
            String str5 = "Wearehappy.";
            String str6 = "    ";
            String str7 = " ";
            String str8 = null;
            String str9 = "";
            String resultStr = replaceSpace(str1);
            System.out.println(resultStr);
        }
    
    }

/**
     * 将字符串中的空格替换为%20
     */
    public class Solution{
    
        /**
         * 
         * @param c
         *            输入的带空格的字符数组
         * @param length
         *            第一个字符到最后一个字符的长度，不是字符数组的长度
         * @return
         */
        public static String replaceSpace(char[] c, int length) {
            // 查询空格的个数
            int count = 0;
            for (int i = 0; i < length; i++) {
                if (c[i] == ' ') {
                    count++;
                }
            }
            // 重新计算新数组的大小
            int newLength = length + count * 2;
            // 从尾到头查找
            int i = length - 1;
            int j = newLength - 1;
            while (i >= 0 && j >= i) {
                if (c[i] == ' ') {
                    c[j--] = '0';
                    c[j--] = '2';
                    c[j--] = '%';
                } else {
                    c[j--] = c[i];
                }
                i--;
            }
            return new String(c);
        }
    
        public static void main(String[] args) {
            String str = "We   are   happy  .";
            int length = str.length();
            char[] olderArray = str.toCharArray();
            // 为简单起见，我们假设给它一个新的空间，空间的大小足以存下替换后的字符
            char[] newArray = new char[100];
            for (int i = 0; i < olderArray.length; i++) {
                newArray[i] = olderArray[i];
            }
            String resultStr = replaceSpace(newArray, length);
            System.out.println(resultStr);
        }
    }

[https_blog.csdn.net_weixin_37672169_article_details_79979710]: https://blog.csdn.net/weixin_37672169/article/details/79979710