118. Pascal's Triangle

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]]

AC:

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