Notice that the row index starts from 0.
In Pascal’s triangle, each number is the sum of the two numbers directly above it.
Follow up:
Could you optimize your algorithm to use only O(k) extra space?
Example 1:
Input: rowIndex = 3
Output: [1,3,3,1]
Example 2:
Input: rowIndex = 0
Output: [1]
Example 3:
Input: rowIndex = 1
Output: [1,1]
class Solution {
public:
vector<int> getRow(int rowIndex) {
vector<int>res(rowIndex+1);
res[0]=1, res[rowIndex]=1;
for(int j=0;j<rowIndex;j++)
for(int i=rowIndex-1;i>0;i--)
res[i]=res[i-1]+res[i];
return res;
}
};