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https://github.com/yuanyu90221/count-good-triplets
https://github.com/yuanyu90221/count-good-triplets
Last synced: 16 days ago
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- Host: GitHub
- URL: https://github.com/yuanyu90221/count-good-triplets
- Owner: yuanyu90221
- Created: 2020-08-17T16:08:26.000Z (over 4 years ago)
- Default Branch: master
- Last Pushed: 2020-08-17T16:08:58.000Z (over 4 years ago)
- Last Synced: 2024-06-19T05:21:55.275Z (7 months ago)
- Language: Go
- Size: 1.95 KB
- Stars: 0
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# count-good-triplets
## 題目解讀：
### 題目來源:
[count-good-triplets](https://leetcode.com/problems/count-good-triplets/)
### 原文:
Given an array of integers arr, and three integers a, b and c. You need to find the number of good triplets.
A triplet (arr[i], arr[j], arr[k]) is good if the following conditions are true:
0 <= i < j < k < arr.length
|arr[i] - arr[j]| <= a
|arr[j] - arr[k]| <= b
|arr[i] - arr[k]| <= c
Where |x| denotes the absolute value of x.
Return the number of good triplets.
### 解讀：
給定一個正整數陣列 arr, 還有三個正整數a, b, c
找尋數對 (arr[i], arr[j], arr[k])符合以下條件
1. 0 <= i < j < k < arr.lenth
2. |arr[i] - arr[j]| <= a
|arr[j] - arr[k]| <= b
|arr[i] - arr[k]| <= c
找尋所有符合條件的數對個數
## 初步解法:
### 初步觀察:
首先
對於數對 (arr[i], arr[j], arr[k])
0 <= i < j < k < arr.length
因此只要固定 i 剩下兩個值 就可以往比i大的直去縮小範圍比對
每次 先固定i 從 0 到 arr.length - 3
j 則會從 i+1 到 arr.length -2
k 則是從 j+1 到 arr.length -1
然後不斷去檢驗條件
### 初步設計:
Given an integer array arr , 3 integer a,b, c
Step 0: let i=0 , count = 0
Step 1: if i > arr.length - 3 go to step 10
Step 2: let j= i + 1
Step 3: if j > arr.length - 2 go to step 1
step 4: let k = j + 1
step 5: if k > arr.length - 1 go to step 3
step 6: check |arr[i] - arr[j]| <= a
|arr[j] - arr[k]| <= b
|arr[i] - arr[k]| <= c satisfy then set count += 1
step 7: set k = k + 1 go to step 5
step 8: set j = j + 1 go to step 3
step 9: set i = i + 1 go to step 1
step 10: return count
## 遇到的困難
### 題目上理解的問題
因為英文不是筆者母語
所以在題意解讀上 容易被英文用詞解讀給搞模糊
### pseudo code撰寫
一開始不習慣把pseudo code寫下來
因此 不太容易把自己的code做解析
### golang table driven test不熟
對於table driven test還不太熟析
所以對於寫test還是耗費不少時間
## 我的github source code
```golang
package count_good_triplets
func countGoodTriplets(arr []int, a int, b int, c int) int {
count := 0
lengthOfArr := len(arr)
for i := 0; i <= lengthOfArr-3; i++ {
for j := i + 1; j <= lengthOfArr-2; j++ {
for k := j + 1; k <= lengthOfArr-1; k++ {
if checkRange(arr[i]-arr[j], arr[j]-arr[k], arr[i]-arr[k], a, b, c) {
count += 1
}
}
}
}
return count
}
func checkRange(d1 int, d2 int, d3 int, a int, b int, c int) bool {
range1 := abs(d1)
range2 := abs(d2)
range3 := abs(d3)
return range1 <= a && range2 <= b && range3 <= c
}
func abs(x int) int {
if x < 0 {
return -x
} else {
return x
}
}
```
## 測資的撰寫
```golang
package count_good_triplets
import "testing"
func Test_countGoodTriplets(t *testing.T) {
type args struct {
arr []int
a int
b int
c int
}
tests := []struct {
name string
args args
want int
}{
{
name: "Example1",
args: args{
arr: []int{3, 0, 1, 1, 9, 7},
a: 7,
b: 2,
c: 3,
},
want: 4,
},
{
name: "Example2",
args: args{
arr: []int{1, 1, 2, 2, 3},
a: 0,
b: 0,
c: 1,
},
want: 0,
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
if got := countGoodTriplets(tt.args.arr, tt.args.a, tt.args.b, tt.args.c); got != tt.want {
t.Errorf("countGoodTriplets() = %v, want %v", got, tt.want)
}
})
}
}
```
## my self record
[golang leetcode 30 20thday](https://hackmd.io/PSGrOqwESUetOjU4ZAUHRA?view)
## 參考文章
[golang test](https://ithelp.ithome.com.tw/articles/10204692)