leetcode Pascal's Triangle

题目连接

https://leetcode.com/problems/pascals-triangle/  

Pascal's Triangle

Description

Given numRows, generate the first numRows of Pascal’s triangle.

For example, given numRows = 5, 
Return

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

 

class Solution {
public:
	vector<vector<int>> generate(int numRows) {
		vector<vector<int>> ans;
		for (int i = 0; i < numRows; i++) {
			vector<int> ret(i + 1);
			ans.push_back(ret);
			for (int j = 0; j < i + 1; j++) {
				ans[i][j] = (!j || i == j) ? 1 : ans[i - 1][j - 1] + ans[i - 1][j];
			}
		}
		return ans;
	}
};