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Pascal's Triangle

Problem statement​

Given an integer numRows, return the first numRows of Pascal's triangle.

In Pascal's triangle, each number is the sum of the two numbers directly above it as shown:

Example 1:

Input: numRows = 5Output: [[1],[1,1],[1,2,1],[1,3,3,1],[1,4,6,4,1]]

Example 2:

Input: numRows = 1Output: [[1]]

Constraints:

  • 1 <= numRows <= 30

My solution​

/**
 * @param {number} numRows
 * @return {number[][]}
 */
var generate = function(numRows) {
    let result = [];
    let prevRow;
    
    for (let i = 1; i <= numRows; i++) {
        const row = Array.from({
            length: i
        }, () => 1)
        
        if (prevRow) {
            for (let j = 1; j < prevRow.length; j++) {
                row[j] = prevRow[j] + prevRow[j - 1];
            }
        }
        
        prevRow = row;
        result.push(row)
    }
    
    return result;
};