給定一個非負整數 numRows，生成楊輝三角的前 numRows 行。

在楊輝三角中，每個數是它左上方和右上方的數的和。

示例:

輸入: 5
輸出:
[
     [1],
    [1,1],
   [1,2,1],
  [1,3,3,1],
 [1,4,6,4,1]
]

C

/**
 * Return an array of arrays.
 * The sizes of the arrays are returned as *columnSizes array.
 * Note: Both returned array and *columnSizes array must be malloced, assume caller calls free().
 */
int** generate(int numRows, int** columnSizes) 
{
    
    int** res=(int**)malloc(sizeof(int*)*numRows);
    *columnSizes=(int*)malloc(sizeof(int)*numRows);
    for(int i=0;i<numRows;i++)
    {
        res[i]=(int*)malloc(sizeof(int)*(i+1));
        res[i][0]=1;
        res[i][i]=1;
        for(int j=1;j<i;j++)
        {
            res[i][j]=res[i-1][j]+res[i-1][j-1];
        } 
        (*columnSizes)[i]=i+1;
    }
    return res;
}
 

C++

class Solution {
public:
    vector<vector<int>> generate(int numRows) 
    {
        vector<vector<int>> res(numRows);
        for(int i=0;i<numRows;i++)
        {
            res[i]=vector<int>(i+1,1);
        }
        if(numRows>2)
        {
            for(int i=2;i<numRows;i++)
            {
                for(int j=1;j<i;j++)
                {
                    res[i][j]=res[i-1][j]+res[i-1][j-1];
                }
            }
        }
        return res;
    }
};
 

python

class Solution:
    def generate(self, numRows):
        """
        :type numRows: int
        :rtype: List[List[int]]
        """
        res=[]
        for i in range(0,numRows):
            res.append([1])
            for j in range(1,i+1):
                if j==i:
                    res[i].append(1)
                else:
                    res[i].append(res[i-1][j]+res[i-1][j-1])
        return res;