数组: 螺旋矩阵

Change-Id: I6c41f251317712d76ce517d0d9769550825cae42

Author: qieguo2016

go/leetcode/54.螺旋矩阵.go

@@ -0,0 +1,88 @@
+/*
+ * @lc app=leetcode.cn id=54 lang=golang
+ *
+ * [54] 螺旋矩阵
+ *
+ * https://leetcode-cn.com/problems/spiral-matrix/description/
+ *
+ * algorithms
+ * Medium (37.01%)
+ * Likes:    215
+ * Dislikes: 0
+ * Total Accepted:    25.1K
+ * Total Submissions: 67.6K
+ * Testcase Example:  '[[1,2,3],[4,5,6],[7,8,9]]'
+ *
+ * 给定一个包含 m x n 个元素的矩阵（m 行, n 列），请按照顺时针螺旋顺序，返回矩阵中的所有元素。
+ * 
+ * 示例 1:
+ * 
+ * 输入:
+ * [
+ * ⁠[ 1, 2, 3 ],
+ * ⁠[ 4, 5, 6 ],
+ * ⁠[ 7, 8, 9 ]
+ * ]
+ * 输出: [1,2,3,6,9,8,7,4,5]
+ * 
+ * 
+ * 示例 2:
+ * 
+ * 输入:
+ * [
+ * ⁠ [1, 2, 3, 4],
+ * ⁠ [5, 6, 7, 8],
+ * ⁠ [9,10,11,12]
+ * ]
+ * 输出: [1,2,3,4,8,12,11,10,9,5,6,7]
+ * 
+ * 
+ */
+func spiralOrder(matrix [][]int) []int {
+	m := len(matrix)
+	if m <= 0 {
+		return []int{}
+	}
+	n := len(matrix[0])
+	if n <= 0 {
+		return []int{}
+	}
+	left, right, up, down := 0, n-1, 0, m-1
+	ret := make([]int, 0)
+	for {
+		// up -> right
+		for j := left; j <= right;j++ {
+			ret = append(ret, matrix[up][j])
+		}
+		up++
+		if up > down {
+			break
+		}
+		// right -> down
+		for i := up; i <= down; i++  {
+			ret = append(ret, matrix[i][right])
+		}
+		right--
+		if left > right {
+			break
+		}
+		// down -> left
+		for j := right; j >= left; j-- {
+			ret = append(ret, matrix[down][j])
+		}
+		down--
+		if up > down {
+			break
+		}
+		// left -> up
+		for i := down; i >= up; i-- {
+			ret = append(ret, matrix[i][left])
+		}
+		left++
+		if left > right {
+			break
+		}
+	}
+	return ret
+}
+