Question

请有人告诉我如何在二叉树中找到或不存在值？我想在二叉树的左或右节点中找到值？

BinarySearchTree.prototype = {

  //more code

  contains: function(value){
    var found       = false,
        current     = this._root

    //make sure there's a node to search
    while(!found && current){

      //if the value is less than the current node's, go left
      if (value < current.value){
        current = current.left;

        //if the value is greater than the current node's, go right
      } else if (value > current.value){
        current = current.right;

        //values are equal, found it!
      } else {
        found = true;
      }
    }

    //only proceed if the node was found
    return found;
  }
}

Answer 1

我建议使用递归方法，而不是使用import java.awt.Dimension; import java.awt.EventQueue; import java.awt.Font; import java.awt.Graphics; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.Timer; /** * @see https://stackoverflow.com/a/37293513/230513 */ public class SimTest { private void display() { JFrame f = new JFrame("SimTest"); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.add(new Simulation(8)); f.pack(); f.setLocationRelativeTo(null); f.setVisible(true); } private static class Simulation extends JPanel { private final Font font = this.getFont().deriveFont(36f); private int count; private int data; Timer t = new Timer(100, new ActionListener() { @Override public void actionPerformed(ActionEvent e) { repaint(); if ((data += 100) == 1000) { t.stop(); System.out.println("Saving results…");//generateCsvFile(); if (--count == 0) { System.out.println("Fin!"); System.exit(0); } else { init(); t.restart(); } } } }); public Simulation(int count) { this.count = count; init(); t.start(); } private void init() { data = 0; } @Override protected void paintComponent(Graphics g) { super.paintComponent(g); g.setFont(font); g.drawString(String.valueOf(data), 8, g.getFontMetrics().getHeight()); } @Override public Dimension getPreferredSize() { return new Dimension(256, 128); } } public static void main(String[] args) { EventQueue.invokeLater(new SimTest()::display); } }进行循环。

while

此函数将返回具有搜索值的节点，如果您只想检查具有特定值的节点是否存在，只需使用function searchBST(rootNode, val) { if (rootNode.key === null) return null; var nodeKey = parseInt(rootNode.val); if (val < nodeKey) { return searchBST(rootNode.left, val); } else if (val > nodeKey) { return searchBST(rootNode.right, val); } else { return rootNode.value; } }和false <编辑返回值/ p>

Answer 2

如果在树中找到了值，您可以离开该函数。

function Node(value) {
    this.value = value;
    // this.left = null;
    // this.right = null;
}

function BinarySearchTree() {
    this._root = null;
}

BinarySearchTree.prototype = {

    insert: function (value) {
        var node = this,
            side = '_root';

        while (node[side]) {
            node = node[side];
            if (value === node.value) {
                return;
            }
            side = value < node.value ? 'left' : 'right';
        }
        node[side] = new Node(value);
    },

    contains: function (value) {
        var current = this._root
        while (current) {
            document.write('value: ' + current.value + '<br>');
            if (value === current.value) {
                return true; // leave the function
            }
            current = value < current.value ? current.left : current.right;
        }
        return false;
    },
};

var tree = new BinarySearchTree(),
    i;

for (i = 0; i < 10; i++) {
    tree.insert(Math.floor(Math.random() * 1000));
}
document.write(tree.contains(42) + '<br>');
tree.insert(42);
document.write(tree.contains(42) + '<br>');
document.write('<pre>' + JSON.stringify(tree, 0, 4) + '</pre>');

如何查找值是否存在于二叉树中

2 个答案: