Merge pull request #2677 from Dev-06-06/feature/1870-min-speed

Add solution for Issue #2660: Minimum Speed to Arrive on Time

Author: hackdartstorm

exercises/1000_programs/medium/1870_min_speed.py

@@ -0,0 +1,28 @@
+import math
+
+def minSpeedOnTime(dist, hour):
+    # If it's impossible to cover all trains even at infinite speed
+    # (need at least 1 hour per train except the last one)
+    if len(dist) - 1 >= hour:
+        return -1
+    left, right = 1, 10**7
+    ans = -1
+    while left <= right:
+        mid = (left + right) // 2
+        # Calculate time taken at speed 'mid'
+        time = 0
+        for i in range(len(dist) - 1):
+            time += (dist[i] + mid - 1) // mid
+        # Last train doesn't need to wait for integer hour
+        time += dist[-1] / mid
+        if time <= hour + 1e-9:
+            ans = mid
+            right = mid - 1
+        else:
+            left = mid + 1
+    return ans
+# Driver code to test locally
+if __name__ == "__main__":
+    print(minSpeedOnTime([1,3,2], 6))    # Expected: 1
+    print(minSpeedOnTime([1,3,2], 2.7))  # Expected: 3
+    print(minSpeedOnTime([1,3,2], 1.9))  # Expected: -1