finish 1228 and 1232

Author: plh97

.vscode/settings.json

@@ -1,4 +1,10 @@
 {
-  "python.linting.enabled": true,
-  "java.format.settings.profile": "GoogleStyle",
+  // "python.linting.enabled": true,
+  // "java.format.settings.profile": "GoogleStyle",
+  "go.inferGopath": true,
+  "go.buildOnSave": "workspace",
+  "go.docsTool": "gogetdoc",
+  "go.lintTool": "golint",
+  "editor.formatOnPaste": true,
+  "editor.formatOnSave": true
 }

algorithm/1228.MissingNumberInArithmeticProgression/README.md

@@ -0,0 +1,32 @@
+# [1228. Missing Number In Arithmetic Progression](https://leetcode.com/problems/check-if-it-is-a-straight-line/)
+
+## 2019/10/20
+
+### 题目 💗[easy]
+
+In some array arr, the values were in arithmetic progression: the values arr[i+1] - arr[i] are all equal for every 0 <= i < arr.length - 1.
+
+Then, a value from arr was removed that was not the first or last value in the array.
+
+Return the removed value.
+
+Example 1:
+
+```bash
+Input: arr = [5,7,11,13]
+Output: 9
+Explanation: The previous array was [5,7,9,11,13].
+```
+
+Example 2:
+
+```bash
+Input: arr = [15,13,12]
+Output: 14
+Explanation: The previous array was [15,14,13,12].
+```
+
+Constraints:
+
+- 3 <= arr.length <= 1000
+- 0 <= arr[i] <= 10^5

algorithm/1228.MissingNumberInArithmeticProgression/main.go

@@ -0,0 +1,42 @@
+package missingnumber
+
+import "math"
+
+func missingNumber(arr []int) int {
+	if len(arr) < 3 {
+		return -1
+	}
+	intMap := make(map[int]int)
+	for i := 1; i < len(arr); i++ {
+		dx := arr[i] - arr[i-1]
+		if _, ok := intMap[dx]; ok {
+			intMap[dx]++
+		} else {
+			intMap[dx] = 1
+		}
+	}
+	max := 0
+	arr1 := []int{}
+	for i := range intMap {
+		arr1 = append(arr1, i)
+	}
+	if intMap[arr1[0]] > intMap[arr1[1]] {
+		max = arr1[0]
+	} else if intMap[arr1[0]] < intMap[arr1[1]] {
+		max = arr1[1]
+	} else {
+		if math.Abs(float64(arr1[0])) < math.Abs(float64(arr1[1])) {
+			max = arr1[0]
+		} else {
+			max = arr1[1]
+		}
+	}
+
+	for i := 1; i < len(arr); i++ {
+		if max != (arr[i] - arr[i-1]) {
+			return arr[i-1] + max
+		}
+	}
+
+	return -1
+}

algorithm/1228.MissingNumberInArithmeticProgression/main_test.go

@@ -0,0 +1,32 @@
+package missingnumber
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+var tcs = []struct {
+	N1  []int
+	ans int
+}{
+	{
+		[]int{5, 7, 11, 13},
+		9,
+	},
+	{
+		[]int{15, 13, 12},
+		14,
+	},
+	{
+		[]int{100, 300, 400},
+		200,
+	},
+}
+
+func Test(t *testing.T) {
+	ast := assert.New(t)
+	for _, tc := range tcs {
+		ast.Equal(tc.ans, missingNumber(tc.N1), "输入:%v", tc)
+	}
+}

algorithm/1232.CheckIfItIsaStraightLine/README.md

@@ -0,0 +1,23 @@
+# [1232. Check If It Is a Straight Line](https://leetcode.com/problems/check-if-it-is-a-straight-line/)
+
+## 2019/08/17
+
+### 题目 💗[easy]
+
+You are given an array coordinates, coordinates[i] = [x, y], where [x, y] represents the coordinate of a point. Check if these points make a straight line in the XY plane.
+
+Example 1:
+
+Input: coordinates = [[1,2],[2,3],[3,4],[4,5],[5,6],[6,7]]
+Output: true
+Example 2:
+
+Input: coordinates = [[1,1],[2,2],[3,4],[4,5],[5,6],[7,7]]
+Output: false
+
+Constraints:
+
+- 2 <= coordinates.length <= 1000
+- coordinates[i].length == 2
+- -10^4 <= coordinates[i][0], coordinates[i][1] <= 10^4
+- coordinates contains no duplicate point.

algorithm/1232.CheckIfItIsaStraightLine/main.go

@@ -0,0 +1,19 @@
+package checkstraightline
+
+func checkStraightLine(coordinates [][]int) bool {
+	if len(coordinates) == 0 || len(coordinates) == 1 {
+		return true
+	}
+	var dx float64 = float64(coordinates[1][0] - coordinates[0][0])
+	var dy float64 = float64(coordinates[1][1] - coordinates[0][1])
+	var dd float64 = dy / dx
+	d0 := coordinates[0]
+	for i, coord := range coordinates {
+		if i == 0 || i == 1 {
+			continue
+		} else if float64(coord[1]-d0[1])/float64(coord[0]-d0[0]) != dd {
+			return false
+		}
+	}
+	return true
+}

algorithm/1232.CheckIfItIsaStraightLine/main_test.go

@@ -0,0 +1,58 @@
+package checkstraightline
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+var tcs = []struct {
+	N1  [][]int
+	ans bool
+}{
+	{
+		[][]int{
+			[]int{1, 2},
+			[]int{2, 3},
+			[]int{3, 4},
+			[]int{4, 5},
+			[]int{5, 6},
+			[]int{6, 7},
+		},
+		true,
+	},
+	{
+		[][]int{
+			[]int{1, 1},
+			[]int{2, 2},
+			[]int{3, 4},
+			[]int{4, 5},
+			[]int{5, 6},
+			[]int{7, 7},
+		},
+		false,
+	},
+	{
+		[][]int{
+			[]int{-3, -2},
+			[]int{-1, -2},
+			[]int{2, -2},
+			[]int{-2, -2},
+			[]int{0, -2},
+		},
+		true,
+	},
+	{
+		[][]int{
+			[]int{-3, -2},
+		},
+		true,
+	},
+}
+
+func Test(t *testing.T) {
+	ast := assert.New(t)
+	for _, tc := range tcs {
+		ast.Equal(tc.ans, checkStraightLine(tc.N1), "输入:%v", tc)
+	}
+}