118 Pascal's Triangle

118 Pascal's Triangle

这道题是easy, 为了凑齐今天的第十题。。。

class Solution:
    # @param {integer} numRows
    # @return {integer[][]}
    def generate(self, numRows):
        if numRows == 0:
            return []
        j = 1
        ans = [[1]]
        while j < numRows:
            row = []
            for i in range(0,j+1):
                if i == 0 or i == j:
                    row.append(1)
                else:
                    row.append(ans[j-1][i-1]+ans[j-1][i])
            ans.append(row)
            j += 1
        return ans