1. Given a string, find its first non-repeating character

1.Given a string, find its first non-repeating character

Examples:

1.intput: “abcdabc”

Output: ‘d’

2.intput: “abbcaaadddbgyyyjuuu”

Output: ‘g’

3.intput: “abcdefabcdefeffeacb”

Output: ‘_’

public Character firstNonRepeatingCharacter(String s){

}

1. 
   The Fibonacci numbers, commonly denoted F(n) form a sequence, called the Fibonacci sequence, such that each number is the sum of the two preceding ones, starting from 0 and 1. That is,
   

F(0) = 0, F(1) = 1

F(n) = F(n - 1) + F(n - 2), for n > 1.

Example 1:

Input: n = 2

Output: 1

Explanation: F(2) = F(1) + F(0) = 1 + 0 = 1.

Example 2:

Input: n = 3

Output: 2

Explanation: F(3) = F(2) + F(1) = 1 + 1 = 2.

Example 3:

Input: n = 4

Output: 3

Explanation: F(4) = F(3) + F(2) = 2 + 1 = 3.

Constraints:

• 
  0 <= n <= 30
  

public int fib(int n) {

}

3. Rotate Image

Medium

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You are given an n x n 2D matrix representing an image, rotate the image by 90 degrees (clockwise).

You have to rotate the image in-place, which means you have to modify the input 2D matrix directly. DO NOT allocate another 2D matrix and do the rotation.

Example 1:



Input: matrix = [[1,2,3],[4,5,6],[7,8,9]]

Output: [[7,4,1],[8,5,2],[9,6,3]]

Example 2:



Input: matrix = [[5,1,9,11],[2,4,8,10],[13,3,6,7],[15,14,12,16]]

Output: [[15,13,2,5],[14,3,4,1],[12,6,8,9],[16,7,10,11]]

Example 3:

Input: matrix = [[1]]

Output: [[1]]

Example 4:

Input: matrix = [[1,2],[3,4]]

Output: [[3,1],[4,2]]

 

Constraints:

• 
  matrix.length == n
  
• 
  matrix[i].length == n
  
• 
  1 <= n <= 20
  
• 
  -1000 <= matrix[i][j] <= 1000
  

4. Search Insert Position

Given a sorted array of distinct integers and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.

You must write an algorithm with O(log n) runtime complexity.

 

Example 1:

Input: nums = [1,3,5,6], target = 5

Output: 2

Example 2:

Input: nums = [1,3,5,6], target = 2

Output: 1

Example 3:

Input: nums = [1,3,5,6], target = 7

Output: 4

Example 4:

Input: nums = [1,3,5,6], target = 0

Output: 0

Example 5:

Input: nums = [1], target = 0

Output: 0

 

Constraints:

• 
  1 <= nums.length <= 10⁴
  
• 
  -10⁴ <= nums[i] <= 10⁴
  
• 
  nums contains distinct values sorted in ascending order.
  
• 
  -10⁴ <= target <= 10⁴