Create 2013-detect-squares.rs

rust/2013-detect-squares.rs

@@ -0,0 +1,35 @@
+use std::collections::HashMap;
+
+struct DetectSquares {
+    points: Vec<(i32, i32)>,
+    counts: HashMap<(i32, i32), i32>
+}
+
+impl DetectSquares {
+
+    fn new() -> Self {
+        Self {
+            points: vec![],
+            counts: HashMap::new()
+        }
+    }
+
+    fn add(&mut self, point: Vec<i32>) {
+        let p = (point[0], point[1]);
+        self.points.push(p);
+        *self.counts.entry(p).or_default() += 1;
+    }
+
+    fn count(&self, point: Vec<i32>) -> i32 {
+        let mut res = 0;
+        let (px, py) = (point[0], point[1]);
+        for (x, y) in self.points.iter() {
+            if (py - y).abs() != (px - x).abs() || *x == px || *y == py {
+                continue;
+            }
+            res += self.counts.get(&(*x, py)).unwrap_or(&0) * self.counts.get(&(px,*y)).unwrap_or(&0);
+        }
+
+        res
+    }
+}