59. Spiral Matrix II ⭐

Medium

Given a positive integer n, generate an n x n matrix filled with elements from 1 to n2 in spiral order.

Example 1:

Input: n = 3
Output: [[1,2,3],[8,9,4],[7,6,5]]

Example 2:

Input: n = 1
Output: [[1]]

Constraints:

• 1 <= n <= 20

解題

這題基本上跟 54.Spiral Matrix 差不多！只是改成把數字填進去。

func generateMatrix(n int) [][]int {
    count := 1
    colBegin, colEnd := 0, n - 1
    rowBegin, rowEnd := 0, n - 1

    ans := make([][]int, 0)
    for i:=0; i<n; i++ {
        ans = append(ans, make([]int, n) )
    }
		fmt.Println(ans)

    for rowBegin <= rowEnd && colBegin <= colEnd {
	// 往右邊
	for i := colBegin; i <= colEnd; i++ {
		ans[rowBegin][i] = count
		count++
	}
	rowBegin++

	// 往下
	for i := rowBegin; i <= rowEnd; i++ {
		ans[i][colEnd] = count
		count++
	}
	colEnd--

	// 往左
	if rowBegin <= rowEnd {
		for i := colEnd; i >= colBegin; i-- {
			ans[rowEnd][i] = count
			count++
		}
	}
	rowEnd--

	// 往上
	if colBegin <= colEnd {
		for i := rowEnd; i >= rowBegin; i-- {
			ans[i][colBegin] = count
			count++
		}
	}
	colBegin++
    }
    
    return ans
}