adding leetcode problem

lectures/04_pointers/README.md

@@ -188,6 +188,4 @@ std::sort( a, a+n );
 
 ## 4.10 Exercises
 
-- [Leetcode problem 905: Sort Array By Parity](https://leetcode.com/problems/sort-array-by-parity/). Solution: [p905_sortarraybyparity.cpp](../../leetcode/p905_sortarraybyparity.cpp)
-- [Leetcode problem 977: Squares of a Sorted Array](https://leetcode.com/problems/squares-of-a-sorted-array/). Solution: [p977_sortedsquare.cpp](../../leetcode/p977_sortedsquare.cpp)
-- [Leetcode problem 1051: Height Checker](https://leetcode.com/problems/height-checker/). Solution: [p1051_heightchecker.cpp](../../leetcode/p1051_heightchecker.cpp)
+- [Leetcode problem 26: Remove Duplicates from Sorted Array](https://leetcode.com/problems/remove-duplicates-from-sorted-array/). Solution: [p26_removeduplicates.cpp](../../leetcode/p26_removeduplicates.cpp)