January Leetcode challenge

Author: ramanaditya

README.md

@@ -100,7 +100,7 @@ Follow the link [https://gitter.im/data-structure-and-algorithms/community](http
         | [April '20 Challenge](https://github.com/ramanaditya/data-structure-and-algorithms/tree/master/leetcode#April-LeetCoding-Challenge--2020) | [May '20 Challenge](https://github.com/ramanaditya/data-structure-and-algorithms/tree/master/leetcode#May-LeetCoding-Challenge--2020) |
         | [June '20 Challenge](https://github.com/ramanaditya/data-structure-and-algorithms/tree/master/leetcode#June-LeetCoding-Challenge--2020) | [July '20 Challenge](https://github.com/ramanaditya/data-structure-and-algorithms/tree/master/leetcode#July-LeetCoding-Challenge--2020) |
         | [August '20 Challenge](https://github.com/ramanaditya/data-structure-and-algorithms/tree/master/leetcode#August-LeetCoding-Challenge--2020) | [September '20 Challenge](https://github.com/ramanaditya/data-structure-and-algorithms/tree/master/leetcode#September-LeetCoding-Challenge--2020) |
-        | [November '20 Challenge](https://github.com/ramanaditya/data-structure-and-algorithms/tree/master/leetcode#November-LeetCoding-Challenge--2020) |  |
+        | [November '20 Challenge](https://github.com/ramanaditya/data-structure-and-algorithms/tree/master/leetcode#November-LeetCoding-Challenge--2020) | [January '20 Challenge](https://github.com/ramanaditya/data-structure-and-algorithms/tree/master/leetcode#January-LeetCoding-Challenge--2021)  |
         
 ## Resources
 

leetcode/README.md

@@ -29,7 +29,8 @@
 | 23.   | July '20 Challenge     | [Search Here](#July-LeetCoding-Challenge--2020) |
 | 24.   | August '20 Challenge   | [Search Here](#August-LeetCoding-Challenge--2020) |
 | 25.   | September '20 Challenge| [Search Here](#September-LeetCoding-Challenge--2020) |
-| 26.   | November  '20 Challenge| [Search Here](#November-LeetCoding-Challenge--2020) |
+| 26.   | November '20 Challenge | [Search Here](#November-LeetCoding-Challenge--2020) |
+| 27.   | January '20 Challenge  | [Search Here](#January-LeetCoding-Challenge--2021) |
 
 - ### **Array**
 
@@ -96,6 +97,7 @@
     | 1572. | <span style="color:green">Easy</span> | [Matrix Diagonal Sum](https://leetcode.com/problems/matrix-diagonal-sum/) | [Python](https://github.com/ramanaditya/data-structure-and-algorithms/blob/master/leetcode/array/matrix-diagonal-sum.py) |
     | 1582. | <span style="color:green">Easy</span> | [Special Positions in a Binary Matrix](https://leetcode.com/problems/special-positions-in-a-binary-matrix/) | [Python](https://github.com/ramanaditya/data-structure-and-algorithms/blob/master/leetcode/array/special-positions-in-a-binary-matrix.py) |
     | 1588. | <span style="color:green">Easy</span> | [Sum of All Odd Length Subarrays](https://leetcode.com/problems/sum-of-all-odd-length-subarrays/) | [Python](https://github.com/ramanaditya/data-structure-and-algorithms/blob/master/leetcode/array/sum-of-all-odd-length-subarrays.py) |
+    | 1640. | <span style="color:green">Easy</span> | [Check Array Formation Through Concatenation](https://leetcode.com/problems/check-array-formation-through-concatenation/) | [Python](https://github.com/ramanaditya/data-structure-and-algorithms/blob/master/leetcode/array/check-array-formation-through-concatenation.py) |
 
 - ### **Binary Search**
 
@@ -427,3 +429,10 @@
     | :---: | :---: | :---: | :--- | :--- |
     | 1 | 1290. | <span style="color:green">Easy</span> | [Convert Binary Number in a Linked List to Integer](https://leetcode.com/problems/convert-binary-number-in-a-linked-list-to-integer/) | [Python](https://github.com/ramanaditya/data-structure-and-algorithms/tree/master/leetcode/linked-list/convert-binary-number-in-a-linked-list-to-integer.py) \| [C](https://github.com/ramanaditya/data-structure-and-algorithms/tree/master/leetcode/linked-list/convert-binary-number-in-a-linked-list-to-integer.c) \| [Java](https://github.com/ramanaditya/data-structure-and-algorithms/tree/master/leetcode/linked-list/convert-binary-number-in-a-linked-list-to-integer.java) |
     | 7 | 445. | <span style="color:orange">Medium</span> | [Add Two Numbers II](https://leetcode.com/problems/add-two-numbers-ii/) | [Python](https://github.com/ramanaditya/data-structure-and-algorithms/tree/master/leetcode/linked-list/add-two-numbers-ii.py) |
+
+- ### **January-LeetCoding-Challenge : 2021**
+
+    | Day | Sl No.| Level | Questions | Solution |
+    | :---: | :---: | :---: | :--- | :--- |
+    | 1 | 1640. | <span style="color:green">Easy</span> | [Check Array Formation Through Concatenation](https://leetcode.com/problems/check-array-formation-through-concatenation/) | [Python](https://github.com/ramanaditya/data-structure-and-algorithms/blob/master/leetcode/array/check-array-formation-through-concatenation.py) |
+    

leetcode/array/check-array-formation-through-concatenation.py

@@ -0,0 +1,68 @@
+"""
+Easy
+1640. [Check Array Formation Through Concatenation](https://leetcode.com/problems/check-array-formation-through-concatenation/)
+
+You are given an array of distinct integers arr and an array of integer arrays pieces, where the integers in pieces are
+distinct. Your goal is to form arr by concatenating the arrays in pieces in any order. However, you are not allowed to
+reorder the integers in each array pieces[i].
+
+Return true if it is possible to form the array arr from pieces. Otherwise, return false.
+
+Example 1:
+Input: arr = [85], pieces = [[85]]
+Output: true
+
+Example 2:
+Input: arr = [15,88], pieces = [[88],[15]]
+Output: true
+Explanation: Concatenate [15] then [88]
+
+Example 3:
+Input: arr = [49,18,16], pieces = [[16,18,49]]
+Output: false
+Explanation: Even though the numbers match, we cannot reorder pieces[0].
+
+Example 4:
+Input: arr = [91,4,64,78], pieces = [[78],[4,64],[91]]
+Output: true
+Explanation: Concatenate [91] then [4,64] then [78]
+
+Example 5:
+Input: arr = [1,3,5,7], pieces = [[2,4,6,8]]
+Output: false
+
+Constraints:
+1 <= pieces.length <= arr.length <= 100
+sum(pieces[i].length) == arr.length
+1 <= pieces[i].length <= arr.length
+1 <= arr[i], pieces[i][j] <= 100
+The integers in arr are distinct.
+The integers in pieces are distinct (i.e., If we flatten pieces in a 1D array, all the integers in this array are distinct).
+"""
+
+# Solutions
+
+
+class Solution:
+    """
+    len(arr) = m
+    len(pieces) = n
+    Time Complexity: O( max(m, n) )
+    Space Complexity: O( n )
+    """
+
+    def canFormArray(self, arr: List[int], pieces: List[List[int]]) -> bool:
+        d = {x[0]: x for x in pieces}
+
+        ind = 0
+        while ind < len(arr):
+            value = d.get(arr[ind])
+            if not value or arr[ind : ind + len(value)] != value:
+                return False
+            ind += len(value)
+
+        return True
+
+
+# Runtime       : 28 ms, faster than 99.69% of Python3 online submissions
+# Memory Usage  : 14.5 MB, less than 16.74% of Python3 online submissions