[Leet Code] 118. Pascal's Triangle 다시 공부 ★

Pascal's Triangle

 

 문제 설명

 

Given an integer numRows, return the first numRows of Pascal's triangle.

In Pascal's triangle, each number is the sum of the two numbers directly above it as shown:

 

 제한 사항

 

• 1 <= numRows <= 30

 

 입출력 예

 

Example 1:

Input : numRows = 5
Output : [[1], [1.1], [1,2,1], [1,3,3,1], [1,4,6,4,1]]

Example 2:

Input : numRows = 1
Output : [[1]]

 

 Python 코드

 

Python 8ms code 

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right

class Solution(object):
    def isSameTree(self, p, q):
     
        if not p and not q:
            return True
        if not p or not q:
            return False
        
        return p.val == q.val and self.isSameTree(p.left, q.left) and self.isSameTree(p.right, q.right)

•  

* 참고 링크 : 

 

 C++ 코드

 

C ++ 100% 0ms code

- String으로 바꾸지 않고 맨 뒤의 값과 맨 앞의 값을 비교하면서 푼 코드

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    bool isSameTree(TreeNode* p, TreeNode* q) {
        if(p == NULL && q == NULL) // if the two nodes are empty nodes, return true
            return true;
        else if((p == NULL && q != NULL) || (p != NULL && q == NULL)) // if only one of the nodes from p and q is emtpy, 2 trees are not equal
            return false;
        else 
            return p->val == q->val && isSameTree(p->left, q->left) && isSameTree(p->right, q->right);
						// First we compare the values in each node from p and q. Then, use a recursive method, call isSameTree function with left nodes of p and q as parameters. Do the same for the right nodes.
    }
};

* 참고 링크 : 

 

 출처

 

https://leetcode.com/problems/pascals-triangle/