LC274 H-Index

class Solution:
    def hIndex(self, citations: List[int]) -> int:
        # time O(NlgN)  space O(1)
        # main idea: first sort and compare citations[i] > i , find max i to meet the condition.   hence k = i+1 
        citations.sort()# here if reverse will slow down the speed 
        size = len(citations)
        i = 0
        while i < size and i < citations[size-1-i]: 
            i += 1 
        return i

class Solution:
    def hIndex(self, citations: List[int]) -> int:
        # time O(N)  space O(N)
        # main idea: first sort and compare citations[i] > i , find max i to meet the condition.   hence k = i+1 
        citations.sort()# here if reverse will slow down the speed 
        size = len(citations)
        l = [0] * (size+1)
        for c in citations:
            if c >= size:
                l[size] += 1
            else:
                l[c] += 1
        
        cnt = 0
        for i in range(size,-1,-1):
            print(i)
            cnt += l[i]
            if cnt >= i:   
                return i  # h  == i here 
        return 0