Added day03 solution

Author: avidLearnerInProgress

30-days-of-code-july/prisonAfterNDays.cpp

@@ -0,0 +1,23 @@
+class Solution {
+public:
+   void prison(vector<int>& cells, int n) {
+        while(n--) {
+            vector<int> prev(8, 0);
+            for(int k=1; k<7; k++) {
+                if(cells[k-1] == cells[k+1]) {
+                     prev[k] = 1;
+                } else {
+                    prev[k] = 0;
+                }
+            }
+            cells = prev;
+        }
+    }
+    vector<int> prisonAfterNDays(vector<int>& cells, int N) {
+        int n = cells.size();
+        if(n == 0) return cells;
+        prison(cells, 1);
+        prison(cells, (N-1) % 14);
+        return cells;
+    }
+};