关于golang:Leetcode专题数组119杨辉三角II

力扣链接：https://leetcode-cn.com/probl…
解题思路：

1. 解法一：应用杨辉三角的解法，返回固定下标的一位数组，该解法须要二维数组

func getRow(rowIndex int) []int {
    res := make([][]int, rowIndex + 1)
    for i := range res {
        res[i] = make([]int, i + 1)
        res[i][0] = 1
        res[i][i] = 1
        for j := 1; j < i; j++ {
            res[i][j] = res[i-1][j-1] + res[i-1][j]
        }
    }
    return res[rowIndex]
}

2.优化一：其实咱们在计算row+1行时，只应用了第row行的数据，所以能够用滚动数组来进行空间上的优化

func getRow(rowIndex int) []int {
    pre, cur := []int, []int
    for i := range rowIndex {
        cur[i] = make([]int, i + 1)
        cur[i][0] = 1
        cur[i][i] = 1
        for j := 1; j < i; j++ {
            cur[j] = pre[j-1] + pre[j]
        }
        pre = cur
    }
    return pre
}