Online Judge►LeetCode

[LeetCode] 654 - Maximum Binary Tree

題意

建造最大二元樹。

解法

照題目描述模擬即可。

程式

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/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {number[]} nums
 * @return {TreeNode}
 */
var constructMaximumBinaryTree = function(nums) {
  
  const build = (left, right) => {
    if ( left > right ) return null;
  
    let max = -1, maxIndex = left;
    for ( let i = left; i <= right ; i ++ ){
      if ( nums[i] > max ){
        max = nums[i];
        maxIndex = i;
      }
    }
    
    const node = new TreeNode(nums[maxIndex]);
    node.left = build(left, maxIndex-1);
    node.right = build(maxIndex+1, right);
    return node;
  }
  return build(0, nums.length - 1);
};