First_non_repeating_number
12345678910111213141516171819
arr = [2, 3, 4, 2, 3, 5]
def first_non_repeating(inp):
count = {}
# First pass: count frequency
for i in inp:
count[i] = count.get(i, 0) + 1
# Second pass: find first non-repeating
for i in inp:
if count[i] == 1:
return i
return None
print(first_non_repeating(arr))
Python
INFO