package sorting;
/**
 * 基數(shù)排序
 * 平均O(d(n+r)),最好O(d(n+r)),最壞O(d(n+r));空間復雜度O(n+r);穩(wěn)定;較復雜
 * d為位數(shù),r為分配后鏈表的個數(shù)
 * @author zeng
 *
 */
public class RadixSort {
	//pos=1表示個位，pos=2表示十位
	public static int getNumInPos(int num, int pos) {
		int tmp = 1;
		for (int i = 0; i < pos - 1; i++) {
			tmp *= 10;
		}
		return (num / tmp) % 10;
	}
	//求得最大位數(shù)d
	public static int getMaxWeishu(int[] a) {
		int max = a[0];
		for (int i = 0; i < a.length; i++) {
			if (a[i] > max)
			        max = a[i];
		}
		int tmp = 1, d = 1;
		while (true) {
			tmp *= 10;
			if (max / tmp != 0) {
				d++;
			} else
			        break;
		}
		return d;
	}
	public static void radixSort(int[] a, int d) {
		int[][] array = new int[10][a.length + 1];
		for (int i = 0; i < 10; i++) {
			array[i][0] = 0;
			// array[i][0]記錄第i行數(shù)據(jù)的個數(shù)
		}
		for (int pos = 1; pos <= d; pos++) {
			for (int i = 0; i < a.length; i++) {
				// 分配過程
				int row = getNumInPos(a[i], pos);
				int col = ++array[row][0];
				array[row][col] = a[i];
			}
			for (int row = 0, i = 0; row < 10; row++) {
				// 收集過程
				for (int col = 1; col <= array[row][0]; col++) {
					a[i++] = array[row][col];
				}
				array[row][0] = 0;
				// 復位，下一個pos時還需使用
			}
		}
	}
	public static void main(String[] args) {
		int[] a = { 49, 38, 65, 197, 76, 213, 27, 50 };
		radixSort(a, getMaxWeishu(a));
		for (int i : a)
		      System.out.print(i + " ");
	}
}