[PGS]두정수사이의합 / lv1 / 15min

https://school.programmers.co.kr/learn/courses/30/lessons/12912

Author: zaqquum

Hongjoo/lv1/두정수사이의합.py

@@ -0,0 +1,16 @@
+def one_to_n(n):
+    return n*(n+1) /2
+def solution(a, b):
+    '''
+    1~ 5 합 = 1+2+3+4+5 = 15 : n(n+1) /2  = 5*6/2 = 15
+    '''
+     # big , small
+    if a > b : 
+        n=a ; m=b
+    elif a < b : 
+        n=b ; m =a
+    else :  # a==b
+        return a
+    answer = one_to_n(n) - one_to_n(m-1)
+    
+    return answer