leetcode-118. Pascal's Triangle

func generate(numRows int) [][]int {

    var arr [][] int;
    arr = make([][]int, numRows);

    var i, j int;
    for i = 0; i < numRows; i++ {
        arr[i] = make([]int, i + 1);
        for j = 0; j <= i; j++ {
            if (j == 0 || i == j) {
                arr[i][j] = 1;
            } else {
                if (i - 1 >= 0 && j - 1 >= 0) {
                    arr[i][j] += arr[i - 1][j - 1];
                }
                if (i - 1 >= 0) {
                    arr[i][j] += arr[i - 1][j];
                }
            }
        }
    }
    return arr;
}