Description
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).
分析
题目的意思是：给定arr和pieces，检查pieces能够由arr构成，但是pieces[i]的顺序不能变。思路我参考了一下别人的思路，首先pieces中如果包含的数不在arr中，则返回False。然后对pieces根据arr的位置进行排序，然后重新拼接成res，如果和arr相同，则表明是符合要求的，否则不能由arr拆分得到pieces。
代码
class Solution:
def canFormArray(self, arr: List[int], pieces: List[List[int]]) -> bool:
for piece in pieces:
if(piece[0] not in arr):
return False
pieces.sort(key=lambda x:arr.index(x[0]))
res=[]
for piece in pieces:
res+=piece
if(res==arr):
return True
else:
return False