Day 15

day15.groovy

@@ -0,0 +1,59 @@
+import groovy.time.TimeCategory; 
+import groovy.time.TimeDuration;
+import groovy.transform.EqualsAndHashCode;
+import groovy.transform.ToString;
+import groovy.transform.TupleConstructor;
+
+
+def HASH(String input) {
+    def cval = 0;
+    for (char c in input.toCharArray()) {
+        int ci = c as int;
+        cval += ci;
+        cval *= 17;
+        cval %= 256;
+    }
+
+    return cval;
+}
+
+{ // Test: HASH
+    assert HASH("HASH") == 52;
+}
+
+def input = new File("input/day15.txt").readLines()
+    .join(",")
+    .split(",");
+
+println(input.collect { HASH(it) }.sum());
+
+def lenses = (0..255).collectEntries { [it, [:]] };
+for (def it in input) {
+    def matcher = it =~ /^([a-zA-Z]+)([-=]{1})([0-9]*)$/;
+    def label = matcher[0][1];
+    def operation = matcher[0][2];
+    def value = matcher[0][3];
+    def labelHash = HASH(label);
+    if (operation == '=') {
+        lenses[labelHash][label] = value.toInteger();
+    } else if (operation == '-') {
+        lenses[labelHash].remove(label);
+    } else {
+        assert false : "Invalid operatioin";
+    }
+}
+
+def focusingPower(def lenses) {
+    def result = 0;
+    for (def entry in lenses) {
+        def boxNumber = entry.key;
+        def slot = 1;
+        for (def lens in entry.value) {
+            result += ((boxNumber + 1) * slot * lens.value);
+            slot += 1;
+        }
+    }
+    return result;
+}
+
+println(focusingPower(lenses));