LeetCode 118 Pascal's Triangle

Problem:

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]
]

Summary:

输出杨辉三角的前n行。

Solution:

方法类似于LeetCode 119 Pascal's Triangle II

 1 class Solution {
 2 public:
 3     vector<vector<int>> generate(int numRows) {
 4         vector<vector<int>> res;
 5         vector<int> v;
 6         for (int i = 0; i < numRows; i++) {
 7             v.resize(i + 1);
 8             v[0] = v[i] = 1;
 9             for (int j = i - 1; j > 0; j--) {
10                 v[j] = v[j - 1] + v[j];
11             }
12             res.push_back(v);
13         }
14         
15         return res;
16     }
17 };

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