day 153

sumOfNumbers.js

@@ -0,0 +1,27 @@
+// Given two integers a and b, which can be positive or negative, find the sum of all the integers between and including them and return it. If the two numbers are equal return a or b.
+
+// Note: a and b are not ordered!
+
+// Examples (a, b) --> output (explanation)
+// (1, 0) --> 1 (1 + 0 = 1)
+// (1, 2) --> 3 (1 + 2 = 3)
+// (0, 1) --> 1 (0 + 1 = 1)
+// (1, 1) --> 1 (1 since both are same)
+// (-1, 0) --> -1 (-1 + 0 = -1)
+// (-1, 2) --> 2 (-1 + 0 + 1 + 2 = 2)
+
+// my original solution
+
+function getSum(a, b) {
+  let sum = 0;
+  for (let i = Math.min(a, b); i <= Math.max(a, b); i++) {
+    sum += i;
+  }
+  return sum;
+}
+
+// what I learned from others' solutions
+
+function GetSum(a, b) {
+  return ((Math.abs(a - b) + 1) * (a + b)) / 2; // formula for return sequential integers
+}