2017: Extract sum()

2017/.editorconfig

@@ -1,4 +1,4 @@
-[*]
+[*.ts]
 charset = utf-8
 insert_final_newline = true
 end_of_line = lf

2017/src/day02.spec.ts

@@ -9,9 +9,7 @@ describe("day 02", () => {
       (line) => line.split(RegExp("\t")).map((c) => parseInt(c)),
     );
 
-    const checksum = spreadsheet
-      .map((row) => row.max() - row.min())
-      .reduce((acc, it) => acc + it);
+    const checksum = spreadsheet.map((row) => row.max() - row.min()).sum();
 
     expect(checksum).toBe(45158);
   });
@@ -38,7 +36,7 @@ describe("day 02", () => {
 
         return n1 > n2 ? n1 / n2 : n2 / n1;
       })
-      .reduce((acc, it) => acc + it);
+      .sum();
 
     expect(checksum).toBe(294);
   });

2017/src/util.ts

@@ -12,6 +12,7 @@ declare global {
   interface Array<T> {
     max(): number;
     min(): number;
+    sum(): number;
   }
 }
 
@@ -28,3 +29,7 @@ Array.prototype.min = function () {
     else return acc;
   });
 };
+
+Array.prototype.sum = function () {
+  return this.reduce((acc, it) => acc + it);
+};