Create number-of-people-aware-of-a-secret.cpp

Author: kamyu104

C++/number-of-people-aware-of-a-secret.cpp

@@ -0,0 +1,20 @@
+// Time:  O(n)
+// Space: O(f)
+
+// dp
+class Solution {
+public:
+    int peopleAwareOfSecret(int n, int delay, int forget) {
+        static const int MOD = 1e9 + 7;
+        vector<int> dp(forget);
+        dp[0] = 1;
+        for (int i = 1; i < n; ++i) {
+            dp[i % forget] = (((i - 1 ? dp[(i - 1) % forget] : 0) - dp[i % forget] + dp[((i - delay) % forget + forget) % forget]) % MOD + MOD) % MOD;
+            
+        }
+        return accumulate(cbegin(dp), cend(dp), 0,
+                          [&](const auto& total, const auto& x) {
+                              return (total + x) % MOD;
+                          });
+    }
+};