leetcode

commit 501153be1cb20b688e3fcd6fe00427897a095712
parent db3649372b10388fb573d70920ee8e735c852c9f
Author: Jack Sangdahl <jack@pngu.org>
Date:   Fri, 24 Oct 2025 21:15:59 -0600

1716. calcluate money in leetcode bank

Diffstat:
M
calculate_money_bank.c
 | 
17
++++-------------
M
calculate_money_bank.py
 | 
15
+++++----------

2 files changed, 9 insertions(+), 23 deletions(-)
diff --git a/calculate_money_bank.c b/calculate_money_bank.c
@@ -10,20 +10,11 @@
  * at the end of the n'th day.
  */
 
+int prog(int next, int prev, int terms) { return (next + prev) * terms / 2; }
+
 int totalMoney(int n) {
-  int begin = 1, end = 7;
-  int sum = 28, total = 0;
-  while (n - 7) {
-    total += sum;
-    sum -= begin++;
-    sum += ++end;
-    n -= 7;
-  }
-  for (int i = 0; i < n; ++i) {
-    total += begin;
-    ++begin;
-  }
-  return total;
+  int q = n / 7, r = n % 7;
+  return prog(28, 28 + (q - 1) * 7, q) + prog(q + 1, q + r, r);
 }
 
 int main() {
diff --git a/calculate_money_bank.py b/calculate_money_bank.py
@@ -11,21 +11,16 @@ at the end of the n'th day.
 
 
 class Solution(object):
+    def prog(self, next, prev, terms):
+        return (next + prev) * terms // 2
+
     def totalMoney(self, n):
         """
         :type n: int
         :rtype: int
         """
-        week = 0
-        day = 1
-        balance = 0
-        for i in range(1, n + 1):
-            balance += week + day
-            day += 1
-            if i % 7 == 0:
-                week += 1
-                day = 1
-        return balance
+        q, r = divmod(n, 7)
+        return self.prog(28, 28 + (q - 1) * 7, q) + self.prog(q + 1, q + r, r)
 
 
 if __name__ == "__main__":