feat: 2001_number_of_pairs_of_interchangeable_rectangles

2001_number_of_pairs_of_interchangeable_rectangles/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "number_of_pairs_of_interchangeable_rectangles"
+version = "0.1.0"

2001_number_of_pairs_of_interchangeable_rectangles/Cargo.toml

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+[package]
+name = "number_of_pairs_of_interchangeable_rectangles"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

2001_number_of_pairs_of_interchangeable_rectangles/src/lib.rs

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+pub struct Solution;
+
+impl Solution {
+    pub fn interchangeable_rectangles(rectangles: Vec<Vec<i32>>) -> i64 {
+        let mut groups = std::collections::HashMap::new();
+
+        for rect in rectangles {
+            let gcd = Solution::gcd(rect[0], rect[1]);
+            let ratio = (rect[0] / gcd, rect[1] / gcd);
+            groups
+                .entry(ratio)
+                .and_modify(|count| *count += 1)
+                .or_insert(1);
+        }
+
+        groups.values().map(|&n| n * (n - 1) / 2).sum()
+    }
+
+    fn gcd(a: i32, b: i32) -> i32 {
+        if a == 0 {
+            b
+        } else if a <= b {
+            Solution::gcd(b % a, a)
+        } else {
+            Solution::gcd(b, a)
+        }
+    }
+}