Create 0329-longest-increasing-path-in-a-matrix.swift

Author: drxlx

swift/0329-longest-increasing-path-in-a-matrix.swift

@@ -0,0 +1,30 @@
+class Solution {
+    func longestIncreasingPath(_ matrix: [[Int]]) -> Int {
+        let rows = matrix.count, cols = matrix[0].count
+        var dp = [[Int]: Int]()
+
+        func dfs(_ r: Int, _ c: Int, _ prev: Int) -> Int {
+            if r < 0 || r == rows || c < 0 || c == cols || matrix[r][c] <= prev {
+                return 0
+            }
+            if dp[[r, c]] != nil {
+                return dp[[r, c]]!
+            }
+            var res = 1
+            res = max(res, 1 + dfs(r + 1, c, matrix[r][c]))
+            res = max(res, 1 + dfs(r - 1, c, matrix[r][c]))
+            res = max(res, 1 + dfs(r, c + 1, matrix[r][c]))
+            res = max(res, 1 + dfs(r, c - 1, matrix[r][c]))
+            dp[[r, c]] = res
+            return res
+        }
+
+        for r in 0..<rows {
+            for c in 0..<cols {
+                dfs(r, c, -1)
+            }
+        }
+
+        return dp.values.max()!
+    }
+}