Formatted question description: https://leetcode.ca/all/1640.html

Question

/**

 1640. 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).

 */

Algorithm

Encode with # to avoid 1,11 and 1,1,1 both contributing to 111. Then brute force way.

Code

Java

public class Check_Array_Formation_Through_Concatenation {
    class Solution {
        public boolean canFormArray(int[] arr, int[][] pieces) {
            StringBuilder sb = new StringBuilder();
            for(int x : arr){ // to avoid 1,11 and 1,1,1 both contributing to 111
                sb.append("#");
                sb.append(x);
                sb.append("#");
            }
            for(int i = 0; i < pieces.length; i++){
                StringBuilder res = new StringBuilder();
                for(int j = 0; j < pieces[i].length; j++){
                    res.append("#");
                    res.append(pieces[i][j]);
                    res.append("#");
                }
                if(!sb.toString().contains(res.toString())){
                    return false;
                }
            }
            return true;
        }
    }

}

Java

class Solution {
    public boolean canFormArray(int[] arr, int[][] pieces) {
        Map<Integer, Integer> map = new HashMap<Integer, Integer>();
        int length = arr.length;
        for (int i = 0; i < length; i++)
            map.put(arr[i], i);
        int[] flatPieces = new int[length];
        for (int[] piece : pieces) {
            int firstNum = piece[0];
            int index = map.getOrDefault(firstNum, -1);
            if (index < 0)
                return false;
            int curLength = piece.length;
            if (index + curLength > length)
                return false;
            System.arraycopy(piece, 0, flatPieces, index, curLength);
        }
        return Arrays.equals(arr, flatPieces);
    }
}

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