Lunski's Clutter

Implement strStr().

Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

Clarification:

What should we return when needle is an empty string? This is a great question to ask during an interview.

For the purpose of this problem, we will return 0 when needle is an empty string. This is consistent to C’s strstr() and Java’s indexOf().

Example 1:

1
2

Input: haystack = "hello", needle = "ll"
Output: 2

Example 2:

1
2

Input: haystack = "aaaaa", needle = "bba"
Output: -1

Example 3:

1
2

Input: haystack = "", needle = ""
Output: 0

Constraints:

1
2
3

0 <= haystack.length, needle.length <= 5 * 10ˆ4

haystack and needle consist of only lower-case English characters.

Write a function to find the longest common prefix string amongst an array of strings.

If there is no common prefix, return an empty string “”.

Example 1:

1
2

Input: strs = ["flower","flow","flight"]
Output: "fl"

Example 2:

1
2
3

Input: strs = ["dog","racecar","car"]
Output: ""
Explanation: There is no common prefix among the input strings.

Constraints:

1
2
3

0 <= strs.length <= 200
0 <= strs[i].length <= 200
strs[i] consists of only lower-case English letters.

Given a 32-bit signed integer, reverse digits of an integer.

Note: Assume we are dealing with an environment that could only store integers within the 32-bit signed integer range: [−231, 231 − 1]. For this problem, assume that your function returns 0 when the reversed integer overflows.

Example 1:

1
2

Input: x = 123
Output: 321

Example 2:

1
2

Input: x = -123
Output: -321

Example 3:

1
2

Input: x = 120
Output: 21

Example 4:

1
2

Input: x = 0
Output: 0

Constraints:

1

-2ˆ31 <= x <= 231 - 1

上次跟大家提到重訓的吃，接下來就是開始動，問題是怎麼動呢？ 其實我一開始也不知道，所以這份課表叫十里坡，在不斷努力後，還是練成了劍神。