Create 0062-unique-paths.swift

Author: drxlx

swift/0062-unique-paths.swift

@@ -0,0 +1,18 @@
+/**
+ * Question Link: https://leetcode.com/problems/unique-paths/
+ */
+
+class Solution {
+    func uniquePaths(_ m: Int, _ n: Int) -> Int {
+        var prevRow = [Int](repeating: 0, count: n)
+        for r in stride(from: m - 1, to: -1, by: -1) {
+            var curRow = [Int](repeating: 0, count: n)
+            curRow[n - 1] = 1
+            for c in stride(from: n - 2, to: -1, by: -1) {
+                curRow[c] = curRow[c + 1] + prevRow[c]
+            }
+            prevRow = curRow
+        }
+        return prevRow[0]
+    }
+}