Update Solution.js

Author: yanglbme

solution/1800-1899/1870.Minimum Speed to Arrive on Time/Solution.js

@@ -4,29 +4,27 @@
  * @return {number}
  */
 var minSpeedOnTime = function (dist, hour) {
-    if (dist.length > Math.ceil(hour)) return -1;
-    let left = 1,
-        right = 10 ** 7;
-    while (left < right) {
-        let mid = (left + right) >> 1;
-        if (arriveOnTime(dist, mid, hour)) {
-            right = mid;
+    if (dist.length > Math.ceil(hour)) {
+        return -1;
+    }
+    const n = dist.length;
+    const m = 10 ** 7;
+    const check = v => {
+        let s = 0;
+        for (let i = 0; i < n; ++i) {
+            const t = dist[i] / v;
+            s += i === n - 1 ? t : Math.ceil(t);
+        }
+        return s <= hour;
+    };
+    let [l, r] = [1, m + 1];
+    while (l < r) {
+        const mid = (l + r) >> 1;
+        if (check(mid)) {
+            r = mid;
         } else {
-            left = mid + 1;
+            l = mid + 1;
         }
     }
-    return left;
+    return l > m ? -1 : l;
 };
-
-function arriveOnTime(dist, speed, hour) {
-    let res = 0.0;
-    let n = dist.length;
-    for (let i = 0; i < n; i++) {
-        let cost = dist[i] / speed;
-        if (i != n - 1) {
-            cost = Math.ceil(cost);
-        }
-        res += cost;
-    }
-    return res <= hour;
-}