119. Pascal's Triangle II

119. Pascal's Triangle II

Given an index k, return the kth row of the Pascal’s triangle.

For example, given k = 3, Return [1,3,3,1].

Note: Could you optimize your algorithm to use only O(k) extra space?

class Solution { public List getRow(int rowIndex) { List list = new ArrayList (rowIndex + 1); list.add(1); if (rowIndex == 0) { return list; } list.add(1); if (rowIndex == 1) { return list; } for (int i = 2; i <= rowIndex; ++i) { list.add(1); for (int j = i - 1; j > 0; --j) { list.set(j, list.get(j) + list.get(j - 1)); } } return list; }}

class Solution { public List getRow(int rowIndex) { List row = new ArrayList<>(); for(int i=0;i<=rowIndex;++i) row.add(findnCr(rowIndex,i)); return row; } public int findnCr(int n, int r){ r = Math.min(r,n-r); double ans=1; for (int i = 0; i < r; ++i){ ans *= (n - i); ans /= (i + 1); } return (int)ans; }}

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