[LeetCode65]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?

Analysis:

滚动数组实现.

C++

vector<int> getRow(int rowIndex) {
      vector<int> result(rowIndex+2,0);
    result[1]=1;
    for(int i=0;i<rowIndex;i++){
        for(int j=rowIndex+1;j>0;j--){
            result[j]= result[j-1]+result[j];
        }
    }
    result.erase(result.begin());
    return result;
    }

java

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

Java