1640 Check Array Formation Through Concatenation

1640 Check Array Formation Through Concatenation.java

class Solution {
    public boolean canFormArray(int[] arr, int[][] pieces) {
        HashMap idx = new HashMap<Integer, Integer>();
        for (int i = 0; i < pieces.length; ++i) {
            idx.put(pieces[i][0], i);
        }
        int cnt = 0;
        while (cnt < arr.length) {
            if (!idx.containsKey(arr[cnt])) return false;
            int p = (int) idx.get(arr[cnt]);
            for (int n : pieces[p]) {
                if (n != arr[cnt++]) return false;
            }
        }
        return true;
    }
}