Create 1515-best-position-for-a-service-centre.js

Author: everthis

1515-best-position-for-a-service-centre.js

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+/**
+ * @param {number[][]} positions
+ * @return {number}
+ */
+const getMinDistSum = function(positions) {
+  const n = positions.length
+  let x = positions.reduce((ac, e) => ac + e[0], 0) / n
+  let y = positions.reduce((ac, e) => ac + e[1], 0) / n
+  
+  const dirs = [[1,0],[-1,0],[0,1],[0,-1]]
+  let res = fn(x, y, positions)
+  let chg = 100
+  while(chg > 1e-6) {
+    let zoom = true
+    for(let [dx, dy] of dirs) {
+      const nx = x + dx * chg
+      const ny = y + dy * chg
+      const nRes = fn(nx, ny, positions)
+      if(nRes < res) {
+        res = nRes
+        x = nx
+        y = ny
+        zoom = false
+        break
+      }
+    }
+    if(zoom) chg /= 2
+  }
+  return res
+};
+
+function fn(x, y, arr) {
+  let res = 0
+  const n = arr.length
+  for(let i = 0; i < n; i++) {
+    res += Math.sqrt((x - arr[i][0]) ** 2 + (y - arr[i][1]) ** 2)
+  }
+  return res
+}