Array Algorithms Question

1. How would you detect a repeated element in an integer array.
2. Write an algorithm and write code to find two numbers in an array whose sum equals a given value
3. Write a program to search for a substring in a main string?
4. Write a C program to reverse a string?
5. Write a C program to reverse the words in a sentence in place?
6. Implement a function that reverses a sentence
Example:
Input: All the best;Do well.
Output: .well Do;best the All

7. An array contains n/2 distint integers and n/2 same element. How to find the repeat (n/2 times) element?
8. Search an integer in a two dimentional integer array, in which each row and colomn are in sorted ascending order?
9. Returns the largest sum of contiguous integers in the array
Example: if the input is (-10, 2, 3, -2, 0, 5, -15), the largest sum is 8.
10. Return the sum two largest integers in an array