EASY 1716. Calculate Money in Leetcode bank

Author: SjxSubham

1716. Calculate Money in Leetcode bank

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+
+
+
+
+class Solution {
+public:
+
+  // Approach 1
+                                    //T.c - O(n)
+
+    int totalMoney(int n) {
+       int total = 0;
+       int monday =1;
+       while(n>0){
+           int money = monday;
+           for(int day=1; day<=min(n,7); day++){
+               total += money; //1
+               money++; //2,3
+           }
+           n -= 7;
+           monday++;
+       }
+       return total;
+
+  // Approach 2
+                              // T.C - O(1)
+      //math Approach A.P series
+      int terms = n/7;
+    int first = 28;
+    int last = 28 +(terms -1)*7; // A.P formula
+    int result = terms *(first + last)/2; // sum of nth term in A.P
+
+    //first week remaining days
+    int start_money = 1+ terms;
+    for( int day = 1; day <=(n%7); day++){
+        result += start_money;
+        start_money++;
+    }
+      return result;
+    }
+}
+
+    return result;
+      
+    }
+};