Create number-of-subarrays-with-and-value-of-k.cpp

Author: kamyu104

C++/number-of-subarrays-with-and-value-of-k.cpp

@@ -0,0 +1,25 @@
+// Time:  O(nlogr)
+// Space: O(logr)
+
+// dp, lc3171
+class Solution {
+public:
+    long long countSubarrays(vector<int>& nums, int k) {
+        int64_t result = 0;
+        unordered_map<int, int> dp;
+        for (const auto& x : nums) {
+            unordered_map<int, int> new_dp;
+            if ((x & k) == k) {
+                ++new_dp[x];
+                for (const auto& [y, c] : dp) {
+                    new_dp[y & x] += c;
+                }
+                if (new_dp.count(k)) {
+                    result += new_dp[k];
+                }
+            }
+            dp = move(new_dp);
+        }
+        return result;
+    }
+};