Update Solution.c

Author: yanglbme

solution/0000-0099/0010.Regular Expression Matching/Solution.c

@@ -1,23 +1,33 @@
-bool isMatch(char* s, char* p) {
-    int m = strlen(s), n = strlen(p);
-    bool** dp = malloc((m + 1) * sizeof(bool*));
-    for (int i = 0; i <= m; i++)
-        dp[i] = calloc(n + 1, sizeof(bool));
-    dp[0][0] = 1;
-    for (int j = 2; j <= n; j++)
-        if (p[j - 1] == '*')
-            dp[0][j] = dp[0][j - 2];
+#define MAX_LEN 1000
+
+char *ss, *pp;
+int m, n;
+int f[MAX_LEN + 1][MAX_LEN + 1];
 
-    for (int i = 1; i <= m; i++)
-        for (int j = 1; j <= n; j++)
-            if (p[j - 1] == '*')
-                dp[i][j] = dp[i][j - 2] || ((p[j - 2] == '.' || p[j - 2] == s[i - 1]) && dp[i - 1][j]);
-            else
-                dp[i][j] = (p[j - 1] == '.' || p[j - 1] == s[i - 1]) && dp[i - 1][j - 1];
+bool dfs(int i, int j) {
+    if (j >= n) {
+        return i == m;
+    }
+    if (f[i][j] != 0) {
+        return f[i][j] == 1;
+    }
+    int res = -1;
+    if (j + 1 < n && pp[j + 1] == '*') {
+        if (dfs(i, j + 2) || (i < m && (ss[i] == pp[j] || pp[j] == '.') && dfs(i + 1, j))) {
+            res = 1;
+        }
+    } else if (i < m && (ss[i] == pp[j] || pp[j] == '.') && dfs(i + 1, j + 1)) {
+        res = 1;
+    }
+    f[i][j] = res;
+    return res == 1;
+}
 
-    bool res = dp[m][n];
-    for (int i = 0; i <= m; i++)
-        free(dp[i]);
-    free(dp);
-    return res;
-}
+bool isMatch(char* s, char* p) {
+    ss = s;
+    pp = p;
+    m = strlen(s);
+    n = strlen(p);
+    memset(f, 0, sizeof(f));
+    return dfs(0, 0);
+}