算法实践篇-计数排序

package com.sort;
/**
 * 计数排序
 * o(n+k)
 * @author Administrator
 *
 */
public class CountingSort {
  public static void countingSort(int []source,int[]target,int k){
    int[] c=new int[k];
    for(int i=0;i<source.length;i++){
      c[source[i]]=c[source[i]]+1;
    }
    for(int i=1;i<k;i++){
      c[i]=c[i]+c[i-1];
    }
    for(int i=source.length-1;i>=0;i--){
      target[c[source[i]]-1]=source[i];
      c[source[i]]=c[source[i]]-1;
    }
  }
  public static void main(String[] args) {
    int [] data=new int[]{1,4,3,8,11,6,19};
    int []target=new int[data.length];
    for(int i=0;i<data.length;i++){
      System.out.print(data[i]+" ");
    }
    System.out.println();
    countingSort(data,target,19+1);
    for(int i=0;i<target.length;i++){
      System.out.print(target[i]+" ");
    }
    System.out.println();
  }

}