Binary Search in forest
Easy Accuracy: 50.08% Submissions: 11830 Points: 2

There are n trees in a forest. The heights of the trees is stored in array tree[], where tree[i] denotes the height of the ith tree in the forest. If the ith tree is cut at a height H, then the wood collected is tree[i] - H, provided tree[i] > H. If the total woods that needs to be collected is exactly equal to k, find the height H at which every tree should be cut (all trees have to be cut at the same height). If it is not possible then return -1 else return H.

Example 1:

Input:
n = 5, k = 4
nums[] = {2, 3, 6, 2, 4}
Output: 3
Explanation: Wood collected by cutting trees
at height 3 = 0 + 0 + (6-3) + 0 + (4-3) = 4
hence 3 is to be subtracted from all numbers.
Since 2 is lesser than 3, nothing gets
subtracted from it.

Example 2:

Input:
n = 6, k = 8
nums[] = {1, 7, 6, 3, 4, 7}
Output: 4
Explanation: Wood collected by cutting trees
at height 4 = 0+(7-4)+(6-4)+0+0+(7-4) = 8

Your Task:
Your task is to complete the function find_height(). This function takes the array tree[ ], and the integers n and k as input parameters and returns the height at which trees have to be cut. If no positive integer value of height is possible, return -1.


Expected Time Complexity: O(n log h)
Expected Auxiliary Space: O(1)


Constraints: 
1 <= n <= 104
1 <= tree[i] <= 103
1 <= k <= 107

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Binary Search in forest

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