[LeetCode] 118. Pascal's Triangle

题目链接：传送门

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]

]

Solution

题意：

生成帕斯卡三角

思路：

按定义构造生成

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