Create Number of Pairs of Interchangeable Rectangles.java

Author: varunu28

Medium/Number of Pairs of Interchangeable Rectangles.java

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+class Solution {
+  public long interchangeableRectangles(int[][] rectangles) {
+    return Arrays.stream(rectangles)
+        .collect(Collectors.groupingBy(
+            e -> ((double) e[0]) / e[1], HashMap::new, Collectors.counting()))
+        .values()
+        .stream()
+        .map(v -> (v * (v - 1)) / 2)
+        .reduce(0L, Long::sum);
+  }
+}