Pascal’s Triangle

Question: Given a non-negative integer numRows, generate the first numRows of Pascal’s triangle.

You may view the full question here.

Approach 1: Let’s dive right into the code —

//Approach 1:
//Runtime: 0ms
//Memory usage: 34MB
class Solution {
    public List<List<Integer>> generate(int numRows) {
        List<List<Integer>> result = new ArrayList();
        if(numRows>=1){
            List<Integer> list = new ArrayList();
            list.add(1);
            result.add(list);
        }
        
        for(int i = 2; i<=numRows; i++){
            compute(result, i-1);
        }
        return result;
    }
    
    private void compute(List<List<Integer>> result, int row){
        List<Integer> prev = result.get(row-1);
        List<Integer> curr = new ArrayList();
        curr.add(1);
        for(int i = 1; i<=row-1; i++){
            curr.add(prev.get(i-1) + prev.get(i));
        }
        curr.add(1);
        result.add(curr);
    }
}

Find more posts here.

Cheers & Chao!