Pascal’s Triangle

Desicription

Given numRows, generate the first numRows of Pascal’s triangle.

For example, given numRows = 5,
Return

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[
[1],
[1,1],
[1,2,1],
[1,3,3,1],
[1,4,6,4,1]
]

Solution

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