add sol

leetcode/41.FirstMissingPositive/sol.go

@@ -0,0 +1,27 @@
+// https://leetcode.com/problems/first-missing-positive
+
+package main
+
+import "fmt"
+
+func firstMissingPositive(nums []int) int {
+	m := make(map[int]bool)
+
+	for _, num := range nums {
+		if num > 0 {
+			m[num] = true
+		}
+	}
+
+	for i := 1; ; i++ {
+		if !m[i] {
+			return i
+		}
+	}
+}
+
+func main() {
+	nums := []int{3, 4, -1, 1}
+
+	fmt.Println(firstMissingPositive(nums))
+}