From dc1f0c4c0096013799416664894c5194dc7e1f52 Mon Sep 17 00:00:00 2001
From: Yuqian Yang <crupest@crupest.life>
Date: Fri, 28 Feb 2025 23:13:39 +0800
Subject: chore(store): move everything to store.

---
 store/works/solutions/leetcode/cpp/639.cpp | 56 ++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100644 store/works/solutions/leetcode/cpp/639.cpp

(limited to 'store/works/solutions/leetcode/cpp/639.cpp')

diff --git a/store/works/solutions/leetcode/cpp/639.cpp b/store/works/solutions/leetcode/cpp/639.cpp
new file mode 100644
index 0000000..ead252e
--- /dev/null
+++ b/store/works/solutions/leetcode/cpp/639.cpp
@@ -0,0 +1,56 @@
+#include <string>
+
+using std::string;
+
+const long long M = 1e9 + 7;
+
+class Solution {
+public:
+  long long f[100010]{0};
+
+  int numDecodings(string s) {
+    f[0] = 1;
+    if (s.front() == '*') {
+      f[1] = 9;
+    } else if (s.front() == '0') {
+      f[1] = 0;
+    } else {
+      f[1] = 1;
+    }
+
+    for (int i = 2; i <= s.size(); i++) {
+      char c = s[i - 1], l = s[i - 2];
+      if (c == '*') {
+        f[i] += f[i - 1] * 9;
+        if (l == '*') {
+          f[i] += f[i - 2] * 15;
+        } else if (l == '1') {
+          f[i] += f[i - 2] * 9;
+        } else if (l == '2') {
+          f[i] += f[i - 2] * 6;
+        }
+        f[i] %= M;
+      } else if (c == '0') {
+        if (l == '1' || l == '2')
+          f[i] += f[i - 2];
+        else if (l == '*')
+          f[i] += f[i - 2] * 2;
+        f[i] %= M;
+      } else {
+        f[i] += f[i - 1];
+        if (l == '*') {
+          if (c <= '6')
+            f[i] += f[i - 2] * 2;
+          else
+            f[i] += f[i - 2];
+        } else if (l == '1')
+          f[i] += f[i - 2];
+        else if (l == '2' && c <= '6')
+          f[i] += f[i - 2];
+        f[i] %= M;
+      }
+    }
+
+    return f[s.size()] % M;
+  }
+};
-- 
cgit v1.2.3