Given a binary tree, find the largest value in each level.
Example 1:
Input:
1
/ \
2 3
Output:
1 3
Explanation:
At 0 level, values of nodes are {1}
Maximum value is 1
At 1 level, values of nodes are {2,3}
Maximum value is 3
Example 2:
Input:
4
/ \
9 2
/ \ \
3 5 7
Output:
4 9 7
Explanation:
At 0 level, values of nodes are {4}
Maximum value is 4
At 1 level, values of nodes are {9,2}
Maximum value is 9
At 2 level, values of nodes are {3,5,7}
Maximum value is 7

Your Task:
You don't need to read input or print anything.Your task is to complete the function maximumValue() that takes root node as input parameter and returns a list of integers containing the maximum value at each level. The size of the resultant list should be equal to the height of the binary tree and result[i] should store the maximum value at level i.
Expected Time Complexity: O(N), where N is the number of nodes.
Expected Auxiliary Space: O(H), where H is the height of binary tree.
Constraints:
1 ≤ Number of nodes ≤ 10^4
1 ≤ Data of a node ≤ 10^5

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