First Unique Character in a String
Given a string s, find the first non-repeating character in it and return its index. If it does not exist, return -1
class Solution(object):
def firstUniqChar(self, s):
hset = collections.Counter(s);
# Traverse the string from the beginning...
for idx in range(len(s)):
# If the count is equal to 1, it is the first distinct character in the list.
if hset[s[idx]] == 1:
return idx
return -1 # If no character appeared exactly once...Related Problems
Given a string s, find the length of the longest substring without repeating characters.
Given a string S and an integer K, return the length of the longest substring of S that contains at most K distinct characters.
Given an integer array nums, you need to find one continuous subarray such that if you only sort this subarray in non-decreasing order, then the whole array will be sorted in non-decreasing order.
Return the shortest such subarray and output its length.
You have observations of n + m 6-sided dice rolls with each face numbered from 1 to 6. n of the observations went missing, and you only have the observations of m rolls. Fortunately, you have also calculated the average value of the n + m rolls.
You are given an integer array rolls of length m where rolls[i] is the value of the ith observation. You are also given the two integers mean and n.
Return an array of length n containing the missing observations such that the average value of the n + m rolls is exactly mean. If there are multiple valid answers, return any of them. If no such array exists, return an empty array.
The average value of a set of k numbers is the sum of the numbers divided by k.
Note that mean is an integer, so the sum of the n + m rolls should be divisible by n + m.