Create restore-the-array.cpp

Author: kamyu104

C++/restore-the-array.cpp

@@ -0,0 +1,26 @@
+// Time:  O(nlogk)
+// Space: O(logk)
+
+class Solution {
+public:
+    int numberOfArrays(string s, int k) {
+        static const int MOD = 1e9 + 7;
+        int klen = to_string(k).length();
+        vector<int> dp(klen + 1);
+        dp[s.length() % dp.size()] = 1;
+        for (int i = s.length() - 1; i >= 0; --i) {
+            dp[i % dp.size()] = 0;
+            if (s[i] == '0') {
+                continue;
+            }
+            for (uint64_t j = i, curr = 0; j < min(uint64_t(i + klen), s.length()); ++j) {
+                curr = curr * 10 + s[j] - '0';
+                if (curr > k) {
+                    break;
+                }
+                dp[i % dp.size()] = (dp[i % dp.size()] + dp[(j + 1) % dp.size()]) % MOD;
+            }
+        }
+        return dp[0];
+    }
+};