[LeetCode]PASCAL Triangle系列

triangle[i+1][j+1] = triangle[i][j]+triangle[i][j+1]

[
[1],
[1,1],
[1,2,1],
[1,3,3,1],
[1,4,6,4,1]
]

class Solution {
public:
vector<int> getRow(int rowIndex) {
// IMPORTANT: Please reset any member data you declared, as
// the same Solution instance will be reused for each test case.
vector<int> prev(1, 1);

if(rowIndex<1)
return prev;

vector<int> row;
for(int i=1; i<rowIndex+1; ++i)
{
for(int j=0; j<i+1; ++j)
{
int left = j>0?prev[j-1]:0;
int right = j<i?prev[j]:0;
row.push_back(left+right);
}
prev = row;
row.clear();
}

return prev;
}
};