基数排序是一种非比较型整数排序算法,其原理是将整数按位数切割成不同的数字,然后按每个位数分别比较。由于整数也可以表达字符串(比如名字或日期)和特定格式的浮点数,所以基数排序也不是只能使用于整数。
基数排序有两种方法:
这三种排序算法都利用了桶的概念,但对桶的使用方法上有明显差异案例看大家发的:
基数排序:根据键值的每位数字来分配桶;
计数排序:每个桶只存储单一键值;
桶排序:每个桶存储一定范围的数值;
//LSD Radix Sortvar counter = [];function radixSort(arr, maxDigit) {var mod = 10;var dev = 1;for (var i = 0; i < maxDigit; i++, dev *= 10, mod *= 10) {for(var j = 0; j < arr.length; j++) {var bucket = parseInt((arr[j] % mod) / dev);if(counter[bucket]==null) {counter[bucket] = [];}counter[bucket].push(arr[j]);}var pos = 0;for(var j = 0; j < counter.length; j++) {var value = null;if(counter[j]!=null) {while ((value = counter[j].shift()) != null) {arr[pos++] = value;}}}}return arr;}
def radix(arr):digit = 0max_digit = 1max_value = max(arr)#找出列表中最大的位数while 10**max_digit < max_value:max_digit = max_digit + 1while digit < max_digit:temp = [[] for i in range(10)]for i in arr:#求出每一个元素的个、十、百位的值t = int((i/10**digit)%10)temp[t].append(i)coll = []for bucket in temp:for i in bucket:coll.append(i)arr = colldigit = digit + 1return arr
/*** 基数排序* 考虑负数的情况还可以参考: https://code.i-harness.com/zh-CN/q/e98fa9*/public class RadixSort implements IArraySort {@Overridepublic int[] sort(int[] sourceArray) throws Exception {// 对 arr 进行拷贝,不改变参数内容int[] arr = Arrays.copyOf(sourceArray, sourceArray.length);int maxDigit = getMaxDigit(arr);return radixSort(arr, maxDigit);}/*** 获取最高位数*/private int getMaxDigit(int[] arr) {int maxValue = getMaxValue(arr);return getNumLenght(maxValue);}private int getMaxValue(int[] arr) {int maxValue = arr[0];for (int value : arr) {if (maxValue < value) {maxValue = value;}}return maxValue;}protected int getNumLenght(long num) {if (num == 0) {return 1;}int lenght = 0;for (long temp = num; temp != 0; temp /= 10) {lenght++;}return lenght;}private int[] radixSort(int[] arr, int maxDigit) {int mod = 10;int dev = 1;for (int i = 0; i < maxDigit; i++, dev *= 10, mod *= 10) {// 考虑负数的情况,这里扩展一倍队列数,其中 [0-9]对应负数,[10-19]对应正数 (bucket + 10)int[][] counter = new int[mod * 2][0];for (int j = 0; j < arr.length; j++) {int bucket = ((arr[j] % mod) / dev) + mod;counter[bucket] = arrayAppend(counter[bucket], arr[j]);}int pos = 0;for (int[] bucket : counter) {for (int value : bucket) {arr[pos++] = value;}}}return arr;}/*** 自动扩容,并保存数据** @param arr* @param value*/private int[] arrayAppend(int[] arr, int value) {arr = Arrays.copyOf(arr, arr.length + 1);arr[arr.length - 1] = value;return arr;}}
function radixSort($arr, $maxDigit = null){if ($maxDigit === null) {$maxDigit = max($arr);}$counter = [];for ($i = 0; $i < $maxDigit; $i++) {for ($j = 0; $j < count($arr); $j++) {preg_match_all('/\d/', (string) $arr[$j], $matches);$numArr = $matches[0];$lenTmp = count($numArr);$bucket = array_key_exists($lenTmp - $i - 1, $numArr)? intval($numArr[$lenTmp - $i - 1]): 0;if (!array_key_exists($bucket, $counter)) {$counter[$bucket] = [];}$counter[$bucket][] = $arr[$j];}$pos = 0;for ($j = 0; $j < count($counter); $j++) {$value = null;if ($counter[$j] !== null) {while (($value = array_shift($counter[$j])) !== null) {$arr[$pos++] = $value;}}}}return $arr;}