feat: Add solution for LeetCode problem 207

Author: WhiteHyun

course-schedule/WhiteHyun.swift

@@ -0,0 +1,43 @@
+//  
+//  207. Course Schedule
+//  https://leetcode.com/problems/course-schedule/description/
+//  Dale-Study
+//  
+//  Created by WhiteHyun on 2024/06/30.
+//  
+
+class Solution {
+  func canFinish(_ numCourses: Int, _ prerequisites: [[Int]]) -> Bool {
+    var graph: [Int: [Int]] = [:]
+    var visited: [Int: Bool] = [:]
+
+    // 그래프 구성
+    for prereq in prerequisites {
+      let course = prereq[0]
+      let prerequisite = prereq[1]
+      graph[course, default: []].append(prerequisite)
+    }
+
+    func dfs(_ course: Int) -> Bool {
+      if visited[course] == true { return false }
+      if visited[course] == false { return true }
+
+      visited[course] = true
+
+      if let prerequisites = graph[course] {
+        for prereq in prerequisites {
+          if !dfs(prereq) { return false }
+        }
+      }
+
+      visited[course] = false
+      return true
+    }
+
+    for course in 0 ..< numCourses {
+      if !dfs(course) { return false }
+    }
+
+    return true
+  }
+}