Leetcode 118.Pascal's Triangle

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This is a simple pascal triangle problem. One matter we have to keep in mind is we may have resize the vector size and allocate them carefully. Hence we have to return the vector.

Code:

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