/*** * @author 无心流泪* 空间换时间*/
public class InterviewExercise {public void mySort(char[] str){int[] hash = new int[52];for(int i=0;i<str.length;i++){if(str[i]>=97) {int key = str[i] - 97;hash[key*2]++; }else{int key = str[i] - 65;hash[key*2+1]++;}}int count = 0;for(int i=0;i<52;i++){while(hash[i]!=0){if(i%2==0){str[count]= (char)(i/2+97);}else{str[count]= (char)((i-1)/2+65);}hash[i]--;count++;}}}public static void main(String[] args) {char[] characterArray = {'R','B','B','b','W','W','B','R','B','w'};new InterviewExercise().mySort(characterArray);for(int i=0;i<characterArray.length;i++)System.out.print(characterArray[i]+" ");}}

public static void main(String[] args) {// A=65,Z=90 a=97,z=122char[] src = { 'R', 'B', 'B', 'b', 'W', 'W', 'B', 'R', 'B', 'w' };src = sortCharsOn(src);for (char c : src) {System.out.print(c + " ");}}/*** O(n)的时间复杂度对给定的字符数组进行排序* * @param src*            原数组* @return 排序后的数组*/private static char[] sortCharsOn(char[] src) {int[] items = new int[54];// 用于保存52个字符char[] des = new char[src.length];for (int i = 0; i < src.length; i++) {if (src[i] < 'z' && src[i] > 'a') { // 小写对应于items中下标为偶数items[(src[i] - 'a') * 2]++;} else if (src[i] < 'Z' && src[i] > 'A') { // 大写对应于items中下标为奇数items[(src[i] - 'A') * 2 + 1]++;}}int index = 0;for (int i = 0; i < items.length; i++) {if (items[i] != 0) {// items[i],就是该字符出现的次数if (i % 2 == 0) {for (int j = 0; j < items[i]; j++) {des[index++] = (char) (i / 2 + 'a');// 转化成小写
                    }} else {for (int j = 0; j < items[i]; j++) {des[index++] = (char) ((i - 1) / 2 + 'A');// 转化成大写
                    }}}}return des;}