Fix challenge ordinal years

Author: cyderize

src/data/challenge/info.js

@@ -99,3 +99,24 @@ export const info = {
     }
   })(),
 }
+
+/// Get ordinal representation of challenge year
+export function nthYear(year) {
+  const n = year - 2008 + 1
+  const s = n % 100;
+  if (s > 3 && s < 21) {
+    return <>{n}<sup>th</sup></>;
+  }
+  switch (s % 10) {
+    case 1: {
+      return <>{n}<sup>st</sup></>;
+    }
+    case 2: {
+      return <>{n}<sup>nd</sup></>;
+    }
+    case 3: {
+      return <>{n}<sup>rd</sup></>;
+    }
+  }
+  return <>{n}<sup>th</sup></>;
+}

src/pages/challenge/2023/index.mdx

@@ -84,7 +84,7 @@ on any questions that arise during the competition.
 
 ### Feedback
 
-This is the 15th time this challenge is being run, and there are many possibilities for comparing CP
+This is the 16th time this challenge is being run, and there are many possibilities for comparing CP
 solvers. The rules try to make a sensible set of choices for the comparison. We welcome any comments
 or suggestions regarding the running of this challenge.
 

src/pages/challenge/2024/index.mdx

@@ -86,7 +86,7 @@ on any questions that arise during the competition.
 
 ### Feedback
 
-This is the 15th time this challenge is being run, and there are many possibilities for comparing CP
+This is the 17th time this challenge is being run, and there are many possibilities for comparing CP
 solvers. The rules try to make a sensible set of choices for the comparison. We welcome any comments
 or suggestions regarding the running of this challenge.
 

src/pages/challenge/2025/index.mdx

@@ -1,4 +1,4 @@
-import { info } from '@/data/challenge/info'
+import { info, nthYear} from '@/data/challenge/info'
 import { Container } from '@/components/Container'
 import { Footer } from '@/components/Footer'
 import { Link } from '@/components/Link'
@@ -86,7 +86,7 @@ on any questions that arise during the competition.
 
 ### Feedback
 
-This is the 15th time this challenge is being run, and there are many possibilities for comparing CP
+This is the {nthYear(year)} time this challenge is being run, and there are many possibilities for comparing CP
 solvers. The rules try to make a sensible set of choices for the comparison. We welcome any comments
 or suggestions regarding the running of this challenge.