add name space
add name space
add name space
https://oj.leetcode.com/problems/pascals-triangle/
modify result when numRows is 0
https://oj.leetcode.com/problems/pascals-triangle-ii/
https://oj.leetcode.com/problems/remove-duplicates-from-sorted-list/
https://oj.leetcode.com/problems/remove-duplicates-from-sorted-array/
remove_element