feat(challenges): add find-closest-number

challenges/find-closest-number/test/1/input.txt

@@ -0,0 +1,8 @@
+3
+6
+1
+2
+3
+4
+5
+6

challenges/find-closest-number/test/1/output.txt

@@ -0,0 +1 @@
+3

challenges/find-closest-number/test/2/input.txt

@@ -0,0 +1,16 @@
+0
+14
+7
+-10
+13
+8
+4
+-7
+-12
+-3
+3
+-9
+6
+-1
+-6
+7

challenges/find-closest-number/test/2/output.txt

@@ -0,0 +1 @@
+-1

challenges/find-closest-number/test/3/input.txt

@@ -0,0 +1,12 @@
+80
+10
+2
+42
+82
+122
+162
+202
+242
+282
+322
+362

challenges/find-closest-number/test/3/output.txt

@@ -0,0 +1 @@
+82

challenges/find-closest-number/test/4/input.txt

@@ -0,0 +1,10 @@
+11
+8
+1
+2
+4
+5
+6
+6
+8
+9

challenges/find-closest-number/test/4/output.txt

@@ -0,0 +1 @@
+9

challenges/find-closest-number/test/5/input.txt

@@ -0,0 +1,8 @@
+4
+6
+2
+5
+6
+7
+8
+9

challenges/find-closest-number/test/5/output.txt

@@ -0,0 +1 @@
+5