添加 problem 498

Author: halfrost

Algorithms/0498. Diagonal Traverse/498. Diagonal Traverse.go

@@ -0,0 +1,140 @@
+package leetcode
+
+// 解法一
+func findDiagonalOrder1(matrix [][]int) []int {
+	if matrix == nil || len(matrix) == 0 || len(matrix[0]) == 0 {
+		return nil
+	}
+	row := len(matrix)
+	col := len(matrix[0])
+	dir := [2][2]int{
+		{-1, 1},
+		{1, -1},
+	}
+	total := row * col
+	res := make([]int, total)
+	var i, x, y, d int
+	for i < total {
+		for x >= 0 && x < row && y >= 0 && y < col {
+			res[i] = matrix[x][y]
+			i++
+			x += dir[d][0]
+			y += dir[d][1]
+		}
+		d = (d + 1) % 2
+		if x == row {
+			x--
+			y += 2
+		}
+		if y == col {
+			y--
+			x += 2
+		}
+		if x < 0 {
+			x = 0
+		}
+		if y < 0 {
+			y = 0
+		}
+	}
+	return res
+}
+
+// 解法二
+func findDiagonalOrder(matrix [][]int) []int {
+	if len(matrix) == 0 {
+		return []int{}
+	}
+	if len(matrix) == 1 {
+		return matrix[0]
+	}
+	// dir = 0 代表从右上到左下的方向， dir = 1 代表从左下到右上的方向 dir = -1 代表上一次转变了方向
+	m, n, i, j, dir, res := len(matrix), len(matrix[0]), 0, 0, 0, []int{}
+	for index := 0; index < m*n; index++ {
+		if dir == -1 {
+			if (i == 0 && j < n-1) || (j == n-1) { // 上边界和右边界
+				i++
+				if j > 0 {
+					j--
+				}
+				dir = 0
+				addTraverse(matrix, i, j, &res)
+				continue
+			}
+			if (j == 0 && i < m-1) || (i == m-1) { // 左边界和下边界
+				if i > 0 {
+					i--
+				}
+				j++
+				dir = 1
+				addTraverse(matrix, i, j, &res)
+				continue
+			}
+		}
+		if i == 0 && j == 0 {
+			res = append(res, matrix[i][j])
+			if j < n-1 {
+				j++
+				dir = -1
+				addTraverse(matrix, i, j, &res)
+				continue
+			} else {
+				if i < m-1 {
+					i++
+					dir = -1
+					addTraverse(matrix, i, j, &res)
+					continue
+				}
+			}
+		}
+		if i == 0 && j < n-1 { // 上边界
+			if j < n-1 {
+				j++
+				dir = -1
+				addTraverse(matrix, i, j, &res)
+				continue
+			}
+		}
+		if j == 0 && i < m-1 { // 左边界
+			if i < m-1 {
+				i++
+				dir = -1
+				addTraverse(matrix, i, j, &res)
+				continue
+			}
+		}
+		if j == n-1 { // 右边界
+			if i < m-1 {
+				i++
+				dir = -1
+				addTraverse(matrix, i, j, &res)
+				continue
+			}
+		}
+		if i == m-1 { // 下边界
+			j++
+			dir = -1
+			addTraverse(matrix, i, j, &res)
+			continue
+		}
+		if dir == 1 {
+			i--
+			j++
+			addTraverse(matrix, i, j, &res)
+			continue
+		}
+		if dir == 0 {
+			i++
+			j--
+			addTraverse(matrix, i, j, &res)
+			continue
+		}
+	}
+	return res
+}
+
+func addTraverse(matrix [][]int, i, j int, res *[]int) {
+	if i >= 0 && i <= len(matrix)-1 && j >= 0 && j <= len(matrix[0])-1 {
+		*res = append(*res, matrix[i][j])
+	}
+}

Algorithms/0498. Diagonal Traverse/498. Diagonal Traverse_test.go

@@ -0,0 +1,67 @@
+package leetcode
+
+import (
+	"fmt"
+	"testing"
+)
+
+type question498 struct {
+	para498
+	ans498
+}
+
+// para 是参数
+// one 代表第一个参数
+type para498 struct {
+	one [][]int
+}
+
+// ans 是答案
+// one 代表第一个答案
+type ans498 struct {
+	one []int
+}
+
+func Test_Problem498(t *testing.T) {
+
+	qs := []question498{
+
+		question498{
+			para498{[][]int{[]int{3}, []int{2}, []int{9}}},
+			ans498{[]int{3, 2, 9}},
+		},
+
+		question498{
+			para498{[][]int{[]int{6, 9, 7}}},
+			ans498{[]int{6, 9, 7}},
+		},
+
+		question498{
+			para498{[][]int{[]int{3}, []int{2}}},
+			ans498{[]int{3, 2}},
+		},
+
+		question498{
+			para498{[][]int{[]int{1, 2, 3}, []int{4, 5, 6}, []int{7, 8, 9}}},
+			ans498{[]int{1, 2, 4, 7, 5, 3, 6, 8, 9}},
+		},
+
+		question498{
+			para498{[][]int{[]int{0}}},
+			ans498{[]int{0}},
+		},
+
+		question498{
+			para498{[][]int{[]int{}}},
+			ans498{[]int{}},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 498------------------------\n")
+
+	for _, q := range qs {
+		_, p := q.ans498, q.para498
+		fmt.Printf("【input】:%v       【output】:%v\n", p, findDiagonalOrder(p.one))
+	}
+	fmt.Printf("\n\n\n")
+}

Algorithms/0498. Diagonal Traverse/README.md

@@ -0,0 +1,39 @@
+# [498. Diagonal Traverse](https://leetcode.com/problems/diagonal-traverse/)
+
+
+## 题目:
+
+Given a matrix of M x N elements (M rows, N columns), return all elements of the matrix in diagonal order as shown in the below image.
+
+**Example:**
+
+    Input:
+    [
+     [ 1, 2, 3 ],
+     [ 4, 5, 6 ],
+     [ 7, 8, 9 ]
+    ]
+    
+    Output:  [1,2,4,7,5,3,6,8,9]
+    
+    Explanation:
+
+![](https://assets.leetcode-cn.com/aliyun-lc-upload/uploads/2018/10/12/diagonal_traverse.png)
+
+**Note:**
+
+The total number of elements of the given matrix will not exceed 10,000.
+
+
+## 题目大意
+
+给定一个含有 M x N 个元素的矩阵（M 行，N 列），请以对角线遍历的顺序返回这个矩阵中的所有元素，对角线遍历如下图所示。
+
+![](https://assets.leetcode-cn.com/aliyun-lc-upload/uploads/2018/10/12/diagonal_traverse.png)
+
+说明: 给定矩阵中的元素总数不会超过 100000 。
+
+## 解题思路
+
+- 给出一个二维数组，要求按照如图的方式遍历整个数组。
+- 这一题用模拟的方式就可以解出来。需要注意的是边界条件：比如二维数组为空，二维数组退化为一行或者一列，退化为一个元素。具体例子见测试用例。