121. Capitals Used Right
A style checker validates how capital letters are used inside a single word made of English letters. The use of capitals is acceptable in exactly three cases: every letter is a capital, no letter is a capital, or only the very first letter is a capital and all the others are lower case.
Return true if the word follows one of these three patterns and false otherwise. A word of one letter is always acceptable. Count the capitals once and compare the count with the length and with the position of the first letter.
Example 1
- Input:
- word = "PYTHON"
- Output:
- true
- Explanation:
All letters are capitals, which is allowed.
Example 2
- Input:
- word = "rUst"
- Output:
- false
- Explanation:
A capital in the second position breaks all three patterns, so the answer is false.
Constraints
1 ≤ word.length ≤ 105
word contains only English letters
How this problem is judged
- Answers
- Your answer must match exactly. Numbers compare by value, so 2 and 2.0 are equal.
Expected complexity
- Time
- O(n)
- Space
- O(1)