题目

字符串的统计字符串

java代码

package com.lizhouwei.chapter5;/** * @Description: 字符串的统计字符串 * @Author: lizhouwei * @CreateDate: 2018/4/24 20:49 * @Modify by: * @ModifyDate: */public class Chapter5_7 {    public String getCountString(String str) {        if (str == null) {            return null;        }        char[] chars = str.toCharArray();        char cur = chars[0];        StringBuilder res = new StringBuilder(cur + "_");        int num = 1;        for (int i = 1; i < chars.length; i++) {            if (chars[i] == chars[i - 1]) {                num++;            } else {                res.append(num + "_" + chars[i] + "_");                cur = chars[i];                num = 1;            }        }        res.append(num);        return res.toString();    }    public char getCharAt(String str, int k) {        if (str == null) {            return 0;        }        char[] chars = str.toCharArray();        char cur = 0;        int num = 0;        int sum = 0;        boolean posi = true;        for (int i = 0; i < chars.length; i++) {            if (chars[i] == '_') {                posi = !posi;            } else if (posi) {                sum += num;                if (sum > k) {                    return cur;                }                num = 0;                cur = chars[i];            } else {                num = num * 10 + chars[i] - '0';            }        }        return cur;    }    //测试    public static void main(String[] args) {        Chapter5_7 chapter = new Chapter5_7();        String str1 = "aaabbadddffc";        String result = chapter.getCountString(str1);        System.out.println("aaabbadddffc的统计字符串：" + result);        char charAtK = chapter.getCharAt(result, 4);        System.out.println(result + "第4位置的字符为：" + charAtK);    }}

结果