Add hints on how the pair functions work

SimonBaars · SimonBaars · commit 624549664e32 · 2024-12-08T08:17:37.000+01:00
diff --git a/src/main/java/com/sbaars/adventofcode/util/AoCUtils.java b/src/main/java/com/sbaars/adventofcode/util/AoCUtils.java
@@ -66,18 +66,22 @@ public static <A> Stream<Pair<A, A>> connectedPairs(Stream<A> l) {
     }).filter(p -> p.a() != null);
   }
 
+  // [A,B,C] -> [(A,B), (B,C)]
   public static <A> Stream<Pair<A, A>> connectedPairs(List<A> l) {
     return range(1, l.size()).mapToObj(i -> pair(l.get(i - 1), l.get(i)));
   }
 
+  // [A,B,C] -> [(A,B)]
   public static <A> Stream<Pair<A, A>> pairs(List<A> l) {
     return range(0, l.size() / 2).mapToObj(i -> new Pair<>(l.get(i * 2), l.get(i * 2 + 1)));
   }
 
+  // [A,B,C] -> [(A,B), (A,C), (B,C)]
   public static <A> Stream<Pair<A, A>> allPairs(List<A> l) {
     return range(0, l.size()).boxed().flatMap(i -> range(i + 1, l.size()).mapToObj(j -> new Pair<>(l.get(i), l.get(j))));
   }
 
+  // [A,B,C] [D,E,F] -> [(A,D), (A,E), (A,F), (B,D), (B,E), (B,F), (C,D), (C,E), (C,F)]
   public static <A, B> Stream<Pair<A, B>> allPairs(List<A> l1, List<B> l2) {
     return range(0, l1.size()).boxed().flatMap(i -> l2.stream().map(b -> new Pair<>(l1.get(i), b)));
   }

Original file line number	Diff line number	Diff line change
`@@ -66,18 +66,22 @@ public static <A> Stream<Pair<A, A>> connectedPairs(Stream<A> l) {`
`66`	`66`	`}).filter(p -> p.a() != null);`
`67`	`67`	`}`
`68`	`68`
	`69`	`+ // [A,B,C] -> [(A,B), (B,C)]`
`69`	`70`	`public static <A> Stream<Pair<A, A>> connectedPairs(List<A> l) {`
`70`	`71`	`return range(1, l.size()).mapToObj(i -> pair(l.get(i - 1), l.get(i)));`
`71`	`72`	`}`
`72`	`73`
	`74`	`+ // [A,B,C] -> [(A,B)]`
`73`	`75`	`public static <A> Stream<Pair<A, A>> pairs(List<A> l) {`
`74`	`76`	`return range(0, l.size() / 2).mapToObj(i -> new Pair<>(l.get(i * 2), l.get(i * 2 + 1)));`
`75`	`77`	`}`
`76`	`78`
	`79`	`+ // [A,B,C] -> [(A,B), (A,C), (B,C)]`
`77`	`80`	`public static <A> Stream<Pair<A, A>> allPairs(List<A> l) {`
`78`	`81`	`return range(0, l.size()).boxed().flatMap(i -> range(i + 1, l.size()).mapToObj(j -> new Pair<>(l.get(i), l.get(j))));`
`79`	`82`	`}`
`80`	`83`
	`84`	`+ // [A,B,C] [D,E,F] -> [(A,D), (A,E), (A,F), (B,D), (B,E), (B,F), (C,D), (C,E), (C,F)]`
`81`	`85`	`public static <A, B> Stream<Pair<A, B>> allPairs(List<A> l1, List<B> l2) {`
`82`	`86`	`return range(0, l1.size()).boxed().flatMap(i -> l2.stream().map(b -> new Pair<>(l1.get(i), b)));`
`83`	`87`	`}`