Create 0010-regular-expression-matching.kt

a93a · web-flow · commit 8d9ab234ab34 · 2023-08-25T20:32:23.000+02:00
diff --git a/kotlin/0010-regular-expression-matching.kt b/kotlin/0010-regular-expression-matching.kt
@@ -0,0 +1,47 @@
+//dp
+class Solution {
+    fun isMatch(s: String, p: String): Boolean {
+        val dp = Array (s.length + 1) { BooleanArray (p.length + 1) }
+        dp[0][0] = true
+
+        for (i in 0..s.length) {
+            for (j in 1..p.length) {
+                if (p[j - 1] == '*') {
+                    dp[i][j] = dp[i][j - 2] || (i > 0 && dp[i - 1][j] && (s[i - 1] == p[j - 2] || p[j - 2] == '.'))
+                } else {
+                    dp[i][j] = i > 0 && dp[i - 1][j - 1] && (s[i - 1] == p[j - 1] || p[j - 1] == '.')
+                }
+            }
+        }
+        
+        return dp[s.length][p.length]
+    }
+}
+
+//recursion + memoization
+class Solution {
+    fun isMatch(s: String, p: String): Boolean {
+        val cache = Array (s.length + 1) { IntArray (p.length + 1) { -1 } }
+        
+        fun dfs(i: Int, j: Int): Int {
+            if (i >= s.length && j >= p.length) 
+                return 1
+            if (j >= p.length) 
+                return 0
+            if (cache[i][j] != -1) 
+                return cache[i][j]
+
+            val charMatched = i < s.length && (s[i] == p[j] || p[j] == '.')
+
+            if (j + 1 < p.length && p[j + 1] == '*')
+                return if (dfs(i, j + 2) == 1 || charMatched && dfs(i + 1, j) == 1) 1 else 0
+            if (charMatched) 
+                return dfs(i + 1, j + 1)
+
+            cache[i][j] == 0
+            return 0
+        }
+
+        return dfs(0, 0) == 1
+    }
+}
