118. Pascal's Triangle

Problem

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

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

Example:

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

Problem Summary

Given a non-negative integer numRows, generate the first numRows rows of Pascal's triangle. In Pascal's triangle, each number is the sum of the numbers to its upper left and upper right.

Solution Approach

• Given an n, print the first n rows of Pascal's triangle.
• Easy problem. Just loop and print according to the generation rules of Pascal's triangle.

Code

package leetcode

func generate(numRows int) [][]int {
	result := [][]int{}
	for i := 0; i < numRows; i++ {
		row := []int{}
		for j := 0; j < i+1; j++ {
			if j == 0 || j == i {
				row = append(row, 1)
			} else if i > 1 {
				row = append(row, result[i-1][j-1]+result[i-1][j])
			}
		}
		result = append(result, row)
	}
	return result
}