Data commit

Task/Josephus-problem/Groovy/josephus-problem.groovy

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+int[] Josephus (int size, int kill, int survivors) {
+    // init user pool
+    def users = new int[size];
+
+    // give initial values such that [0] = 1 (first person) [1] = 2 (second person) etc
+    users.eachWithIndex() {obj, i -> users[i] = i + 1};
+
+    // keep track of which person we are on (ranging from 1 to kill)
+    def person = 1;
+
+    // keep going until we have the desired number of survivors
+    while (users.size() > survivors)
+    {
+        // for each person, if they are the kill'th person, set them to -1 to show eliminated
+        users.eachWithIndex() {obj, i ->
+            if (person++ % kill == 0) {
+                users[i] = -1;
+            }
+
+            // if person overflowed kill then reset back to 1
+            if (person > kill) {person = 1;}
+        }
+
+        // clear out all eliminated persons
+        users = users.findAll{w -> w >= 0};
+    }
+
+    // resulting set is the safe positions
+    return users;
+}
+
+// Run some test cases
+
+println "Final survivor for n = 10201 and k = 17: " + Josephus(10201,17,1)[0];
+
+println "4 safe spots for n = 10201 and k = 17: " + Josephus(10201,17,4);