[20250911] PGM / LV2 / 시소 짝꿍 / 김수연

suyeun84/202509/11 PGM LV2 시소 짝꿍.md

@@ -0,0 +1,23 @@
+```java
+import java.util.*;
+class Solution {
+    public long solution(int[] weights) {
+    	long answer = 0;
+        Arrays.sort(weights);
+        Map<Double, Integer> map = new HashMap<>();
+        for(int i : weights) {
+    		double a = i*1.0;
+    		double b = (i*2.0)/3.0;
+    		double c = (i*1.0)/2.0;
+    		double d = (i*3.0)/4.0;
+    		if(map.containsKey(a)) answer += map.get(a);
+    		if(map.containsKey(b)) answer += map.get(b);
+    		if(map.containsKey(c)) answer += map.get(c);
+    		if(map.containsKey(d)) answer += map.get(d);
+    		map.put((i*1.0), map.getOrDefault((i*1.0), 0)+1);
+        }
+
+        return answer;
+    }
+}
+```