Add solution 1539

leetcode/1539.Kth-Missing-Positive-Number/1539. Kth Missing Positive Number.go

@@ -0,0 +1,20 @@
+package leetcode
+
+func findKthPositive(arr []int, k int) int {
+	positive, index := 1, 0
+	for index < len(arr) {
+		if arr[index] != positive {
+			k--
+		} else {
+			index++
+		}
+		if k == 0 {
+			break
+		}
+		positive++
+	}
+	if k != 0 {
+		positive += k - 1
+	}
+	return positive
+}

leetcode/1539.Kth-Missing-Positive-Number/1539. Kth Missing Positive Number_test.go

@@ -0,0 +1,48 @@
+package leetcode
+
+import (
+	"fmt"
+	"testing"
+)
+
+type question1539 struct {
+	para1539
+	ans1539
+}
+
+// para 是参数
+// one 代表第一个参数
+type para1539 struct {
+	arr []int
+	k   int
+}
+
+// ans 是答案
+// one 代表第一个答案
+type ans1539 struct {
+	one int
+}
+
+func Test_Problem1539(t *testing.T) {
+
+	qs := []question1539{
+
+		{
+			para1539{[]int{2, 3, 4, 7, 11}, 5},
+			ans1539{9},
+		},
+
+		{
+			para1539{[]int{1, 2, 3, 4}, 2},
+			ans1539{6},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 1539------------------------\n")
+
+	for _, q := range qs {
+		_, p := q.ans1539, q.para1539
+		fmt.Printf("【input】:%v      【output】:%v      \n", p, findKthPositive(p.arr, p.k))
+	}
+	fmt.Printf("\n\n\n")
+}

leetcode/1539.Kth-Missing-Positive-Number/README.md

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+# [1539. Kth Missing Positive Number](https://leetcode.com/problems/kth-missing-positive-number/)
+
+## 题目
+
+Given an array `arr` of positive integers sorted in a **strictly increasing order**, and an integer `k`.
+
+*Find the* `kth` *positive integer that is missing from this array.*
+
+**Example 1:**
+
+```
+Input: arr = [2,3,4,7,11], k = 5
+Output: 9
+Explanation: The missing positive integers are [1,5,6,8,9,10,12,13,...]. The 5th missing positive integer is 9.
+```
+
+**Example 2:**
+
+```
+Input: arr = [1,2,3,4], k = 2
+Output: 6
+Explanation: The missing positive integers are [5,6,7,...]. The 2nd missing positive integer is 6.
+```
+
+**Constraints:**
+
+- `1 <= arr.length <= 1000`
+- `1 <= arr[i] <= 1000`
+- `1 <= k <= 1000`
+- `arr[i] < arr[j]` for `1 <= i < j <= arr.length`
+
+## 题目大意
+
+给你一个 **严格升序排列** 的正整数数组 `arr` 和一个整数 `k` 。请你找到这个数组里第 `k` 个缺失的正整数。
+
+## 解题思路
+
+- 简单题。用一个变量从 1 开始累加，依次比对数组中是否存在，不存在的话就把 k - -，直到 k 为 0 的时候即是要输出的值。特殊情况，missing positive 都在数组之外，如例子 2 。
+
+## 代码
+
+```go
+package leetcode
+
+func findKthPositive(arr []int, k int) int {
+	positive, index := 1, 0
+	for index < len(arr) {
+		if arr[index] != positive {
+			k--
+		} else {
+			index++
+		}
+		if k == 0 {
+			break
+		}
+		positive++
+	}
+	if k != 0 {
+		positive += k - 1
+	}
+	return positive
+}
+```