63 lines
1.4 KiB
Java
63 lines
1.4 KiB
Java
/**
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* @Description:基数排序
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* @Author: Hoda
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* @Date: Create in 2019-07-25
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* @Modified By:
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* @Modified Date:
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*/
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public class RadixSort {
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/**
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* 基数排序
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*
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* @param arr
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*/
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public static void radixSort(int[] arr) {
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int max = arr[0];
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for (int i = 0; i < arr.length; i++) {
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if (arr[i] > max) {
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max = arr[i];
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}
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}
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// 从个位开始，对数组arr按"指数"进行排序
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for (int exp = 1; max / exp > 0; exp *= 10) {
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countingSort(arr, exp);
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}
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}
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/**
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* 计数排序-对数组按照"某个位数"进行排序
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*
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* @param arr
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* @param exp 指数
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*/
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public static void countingSort(int[] arr, int exp) {
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if (arr.length <= 1) {
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return;
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}
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// 计算每个元素的个数
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int[] c = new int[10];
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for (int i = 0; i < arr.length; i++) {
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c[(arr[i] / exp) % 10]++;
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}
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// 计算排序后的位置
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for (int i = 1; i < c.length; i++) {
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c[i] += c[i - 1];
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}
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// 临时数组r，存储排序之后的结果
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int[] r = new int[arr.length];
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for (int i = arr.length - 1; i >= 0; i--) {
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r[c[(arr[i] / exp) % 10] - 1] = arr[i];
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c[(arr[i] / exp) % 10]--;
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}
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for (int i = 0; i < arr.length; i++) {
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arr[i] = r[i];
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}
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}
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}
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