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

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

         return res;
     }
 };

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;    }};