[20251003] PGM / Lv3 / 주사위 고르기 / 이강현

lkhyun/202510/03 PGM Lv3 주사위 고르기.md

@@ -0,0 +1,97 @@
+```java
+import java.util.*;
+
+class Solution {
+    static int n;
+    static int maxWin;
+    static int[] answer;
+
+    public int[] solution(int[][] dice) {
+        n = dice.length;
+        maxWin = 0;
+
+        combination(new boolean[n], 0, 0, dice);
+
+        return answer;
+    }
+
+    void combination(boolean[] selected, int idx, int count, int[][] dice) {
+        if (count == n / 2) {
+            int winCount = getWinCount(selected, dice);
+
+            if (winCount > maxWin) {
+                maxWin = winCount;
+                answer = getSelectedDice(selected);
+            }
+            return;
+        }
+
+        if (idx == n) return;
+
+        selected[idx] = true;
+        combination(selected, idx + 1, count + 1, dice);
+
+        selected[idx] = false;
+        combination(selected, idx + 1, count, dice);
+    }
+
+    int getWinCount(boolean[] selected, int[][] dice) {
+        List<Integer> aList = new ArrayList<>();
+        List<Integer> bList = new ArrayList<>();
+
+        makeSum(selected, dice, true, 0, 0, aList);
+        makeSum(selected, dice, false, 0, 0, bList);
+
+        Collections.sort(bList);
+
+        int win = 0;
+        for (int a : aList) {
+            win += lowerBound(bList, a);
+        }
+
+        return win;
+    }
+
+    void makeSum(boolean[] selected, int[][] dice, boolean isA, int idx, int sum, List<Integer> list) {
+        if (idx == n) {
+            list.add(sum);
+            return;
+        }
+
+        if (selected[idx] == isA) {
+            for (int num : dice[idx]) {
+                makeSum(selected, dice, isA, idx + 1, sum + num, list);
+            }
+        } else {
+            makeSum(selected, dice, isA, idx + 1, sum, list);
+        }
+    }
+
+    int lowerBound(List<Integer> list, int target) {
+        int left = 0;
+        int right = list.size();
+
+        while (left < right) {
+            int mid = (left + right) / 2;
+            if (list.get(mid) < target) {
+                left = mid + 1;
+            } else {
+                right = mid;
+            }
+        }
+
+        return left;
+    }
+
+    int[] getSelectedDice(boolean[] selected) {
+        int[] result = new int[n / 2];
+        int idx = 0;
+        for (int i = 0; i < n; i++) {
+            if (selected[i]) {
+                result[idx++] = i + 1;
+            }
+        }
+        return result;
+    }
+}
+```