Given a non-negative integer numRows, generate the first numRows of Pascal's triangle.
In Pascal's triangle, each number is the sum of the two numbers directly above it.
Example:
Input: 5
Output:
[
[1],
[1,1],
[1,2,1],
[1,3,3,1],
[1,4,6,4,1]
]
Accepted
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class Solution {
public:
vector<vector<int>> generate(int numRows) {
vector<vector<int>> res(numRows, vector<int>());
if(0==numRows)return res;
res[0].push_back(1);
if(1==numRows)return res;
for (int i = 1; i < numRows; ++i)
for (int j = 0; j < i+1; ++j)
{
if (res[i].size() < i+1) res[i].resize(i+1);
if (0 == j || i == j)res[i][j] = 1;
else
{
if (j) res[i][j] += res[i - 1][j - 1];
if (i >= j) res[i][j] += res[i - 1][j];
}
}
return res;
}
};