pascals-triangle-ii.md

Code

func getRow(rowIndex int) []int {
	prevRow := []int{}
	for i := 0; i < rowIndex+1; i++ {
		row := make([]int, i+1)
		row[0] = 1
		row[i] = 1

		for j, val := range row {
			if val != 1 {
				row[j] = prevRow[j] + prevRow[j-1]
			}
		}

		prevRow = row
		if i == rowIndex {
			return row
		}
	}

	return []int{}
}

Solution in mind

• Populate triangle, row by row. We keep track of previous row (prevRow) and the current row (row) is created by summing values from the previous.

• In every row, the first and last element are 1. Thus we can distinguish elements to be calculated as those that do not have their value equal to 1.

• A value at index j in a row can be calculated as the sum of j and j-1 values of the previous row.

• As we populate these rows, we return the row created when i == rowIndex.