118.杨辉三角

/*
 * @lc app=leetcode.cn id=118 lang=typescript
 * @lcpr version=30204
 *
 * [118] 杨辉三角
 */


function generate(numRows: number): number[][] {
    if (numRows === 0) return [];
    let res: number[][] = [];
    res.push([1])
    for (let i = 1; i < numRows; i++) {
        let row: number[] = [];
        row.push(1)
        for (let j = 1; j < i; j++) {
            row.push(res[i - 1][j - 1] + res[i - 1][j] || 0);
        }
        row.push(1)
        res.push(row)
    }
    return res;
};