feat(heap): ✨分治法优化973

Author: descire

Heap/973/solution2.js

@@ -0,0 +1,62 @@
+/**
+ * https://leetcode-cn.com/problems/k-closest-points-to-origin/submissions/
+ * 
+ * 973. 最接近原点的 K 个点
+ * 
+ * Medium
+ * 
+ * 192ms 100.00%
+ * 48mb 70%
+ * 
+ * O(n)
+ */
+const kClosest = (points, K) => {
+  if (K === points.length) {
+    return points;
+  }
+  findKClosest(points, 0, points.length - 1, K);
+  return points.slice(0, K);
+}
+
+function swap(points, i, j) {
+  if (i === j) {
+    return;
+  }
+  const divisionPoint = points[i];
+  points[i] = points[j];
+  points[j] = divisionPoint;
+}
+
+function getDistance(points) {
+  const [x, y] = points;
+  // 这里没必要取根号，可以节省点时间复杂度
+  return x ** 2 + y ** 2;
+}
+
+function findKClosest(points, startIndex, endIndex, K) {
+  if (startIndex > endIndex) {
+    return;
+  }
+
+  const startItemDistance = getDistance(points[startIndex]);
+
+  let divisionPoint = startIndex;
+
+  swap(points, startIndex, endIndex);
+
+  for (let i = startIndex; i < endIndex; i++) {
+    if (getDistance(points[i]) < startItemDistance) {
+      swap(points, i, divisionPoint);
+      divisionPoint++;
+    }
+  }
+  swap(points, divisionPoint, endIndex);
+
+  if (divisionPoint + 1 === K) {
+    return
+  } else if (divisionPoint + 1 < K) {
+    findKClosest(points, divisionPoint + 1, endIndex, K);
+  } else {
+    findKClosest(points, startIndex, divisionPoint - 1, K);
+  }
+}