二叉樹刪除節點功能不起作用

public void removeNode(int data) { 
    deleteNode(root, data); 
} 

public Node deleteNode(Node focus, int data) { 
    if(focus == null) { 
     System.out.println("Tree empty"); 
     return null; 
    } 
    else if(data < focus.data) { 
     deleteNode(focus.leftchild, data); 
    } 
    else if(data > focus.data) { 
     deleteNode(focus.rightchild, data); 
    } 
    else { 
     // No child 
     if(focus.leftchild == null && focus.rightchild == null) { 
      focus = null; 
     } 
     // one child 
     else if(focus.leftchild == null) { 
      focus = focus.rightchild; 
      System.out.println("here"); 
     } 
     else if(focus.rightchild == null) { 
      focus = focus.leftchild; 
     } 
     // 2 children 
     else { 
      Node temp = findMin(focus.rightchild); 
      focus.data = temp.data; 
      deleteNode(focus.rightchild, temp.data); 
     } 
    } 
    return focus; 
} 

public Node findMin(Node focus) { 
    while(focus.leftchild != null) { 
     focus = focus.leftchild; 
    } 
    return focus; 
}

我寫了上面的代碼來刪除二叉搜索樹中的一個節點。但由於某些原因，當我運行preordertraversal函數來打印所有節點時，我發現該節點沒有被刪除。有人可以告訴我爲什麼一個節點沒有被刪除。該功能似乎是正確的。二叉樹刪除節點功能不起作用

來源

2017-03-31 Vineeth Subbaraya

設置'focus = null'或'focus = focus.rightchild'不會刪除節點'focus'。您只需將變量'focus'（只存在於此函數中）指向另一個節點（或'null'）。相反，您必須將Node ** ** parent **中的變量設置爲不同的值！ –

好吧！將嘗試。謝謝！ –

我想到了！問題是我沒有以正確的方式遍歷樹。另外我在有兩個孩子的情況下犯了一個錯誤。我沒有設置正確的焦點.rightchild。這裏是更新代碼

public Node deleteNode(Node focus, int data) { 
    if(focus == null) { 
     System.out.println("Tree empty"); 
     return null; 
    } 
    else if(data < focus.data) { 
     focus.leftchild = deleteNode(focus.leftchild, data); 
    } 
    else if(data > focus.data) { 
     focus.rightchild = deleteNode(focus.rightchild, data); 
    } 
    else { 
     // No child 
     if(focus.leftchild == null && focus.rightchild == null) { 
      focus = null; 
     } 
     // one child 
     else if(focus.leftchild == null) { 
      focus = focus.rightchild; 
      System.out.println("here"); 
     } 
     else if(focus.rightchild == null) { 
      focus = focus.leftchild; 
     } 
     // 2 children 
     else { 
      Node temp = findMin(focus.rightchild); 
      focus.data = temp.data; 
      focus.rightchild = deleteNode(focus.rightchild, temp.data); 
     } 
    } 
    return focus; 
}

來源

2017-03-31 21:53:37

二叉樹刪除節點功能不起作用

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