归并排序

Posted 2020-08-20 猫儿爹

主要思想是先对序列进行分割，然后再进行归并排序。
如一个数组[1,2,3,4,5,6]
第一次分割为[1,2,3],[4,5,6]
第二次分割为[1,2],[3],[4,5],[6]
第三次分割为[1],[2],[3],[4],[5,[6]
第一次归并排序为[1],[2];[4],[5]
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以此类推

public class MergeSort {
    private double[] bridge;
    
    public MergeSort(double [] sorted){
        
        if(sorted.length==0){
            throw new NullPointerException("size is null");
            
        }
        int sorted_length=sorted.length;
        bridge=new double[sorted_length];
        
        
        
    }

    
    public void mergeso(double [] obj,int left,int right){
        
        while(left<right){
            
            int center=(left+right)/2;
            
            mergeso(obj,left,center);
            mergeso(obj,center+1,right);
            merge(obj,left,center,right);
            
            
            
        }
        
        
    }
    
    
    
    public void  merge(double [] obj,int left,int center,int right){
        int mid=center+1;
        int tem1=left;
        int tem2=left;
        while(left<=center && mid<=right){
            
            if(obj[left]<obj[mid]){
                
                bridge[tem1++]=obj[left++];
                
            }
            else{
                
                bridge[tem1++]=obj[mid++];
                
            }
            
        }
        
        while(left<=center){
            
            bridge[tem1++]=obj[left++];
            
        }
        
        while(mid<=center){
            
            bridge[tem1++]=obj[mid++];
            
        }
        
        copy(obj,tem2,right);
        
    }
    
    
    public void copy(double [] obj,int left,int right){
        
        while(left<=right){
            
            obj[left]=bridge[left];
            left++;
            
        }
        
    }
}