Given a function fn, an array of arguments args, and an interval time t, return a cancel function cancelFn.
After a delay of cancelTimeMs, the returned cancel function cancelFn will be invoked.
setTimeout(cancelFn, cancelTimeMs)
The function fn should be called with args immediately and then called again every t milliseconds until cancelFn is called at cancelTimeMs ms.
Example 1:
Input: fn = (x) => x * 2, args = [4], t = 35
Output:
[
{"time": 0, "returned": 8},
{"time": 35, "returned": 8},
{"time": 70, "returned": 8},
{"time": 105, "returned": 8},
{"time": 140, "returned": 8},
{"time": 175, "returned": 8}
]
Explanation:
const cancelTimeMs = 190;
const cancelFn = cancellable((x) => x * 2, [4], 35);
setTimeout(cancelFn, cancelTimeMs);
Every 35ms, fn(4) is called. Until t=190ms, then it is cancelled.
1st fn call is at 0ms. fn(4) returns 8.
2nd fn call is at 35ms. fn(4) returns 8.
3rd fn call is at 70ms. fn(4) returns 8.
4th fn call is at 105ms. fn(4) returns 8.
5th fn call is at 140ms. fn(4) returns 8.
6th fn call is at 175ms. fn(4) returns 8.
Cancelled at 190ms
Example 2:
Input: fn = (x1, x2) => (x1 * x2), args = [2, 5], t = 30
Output:
[
{"time": 0, "returned": 10},
{"time": 30, "returned": 10},
{"time": 60, "returned": 10},
{"time": 90, "returned": 10},
{"time": 120, "returned": 10},
{"time": 150, "returned": 10}
]
Explanation:
const cancelTimeMs = 165;
const cancelFn = cancellable((x1, x2) => (x1 * x2), [2, 5], 30)
setTimeout(cancelFn, cancelTimeMs)
Every 30ms, fn(2, 5) is called. Until t=165ms, then it is cancelled.
1st fn call is at 0ms
2nd fn call is at 30ms
3rd fn call is at 60ms
4th fn call is at 90ms
5th fn call is at 120ms
6th fn call is at 150ms
Cancelled at 165ms
Example 3:
Input: fn = (x1, x2, x3) => (x1 + x2 + x3), args = [5, 1, 3], t = 50
Output:
[
{"time": 0, "returned": 9},
{"time": 50, "returned": 9},
{"time": 100, "returned": 9},
{"time": 150, "returned": 9}
]
Explanation:
const cancelTimeMs = 180;
const cancelFn = cancellable((x1, x2, x3) => (x1 + x2 + x3), [5, 1, 3], 50)
setTimeout(cancelFn, cancelTimeMs)
Every 50ms, fn(5, 1, 3) is called. Until t=180ms, then it is cancelled.
1st fn call is at 0ms
2nd fn call is at 50ms
3rd fn call is at 100ms
4th fn call is at 150ms
Cancelled at 180ms
Constraints:
fn is a functionargs is a valid JSON array1 <= args.length <= 1030 <= t <= 10010 <= cancelTimeMs <= 500This approach leverages JavaScript's setInterval function to repeatedly invoke a function at specified intervals. The function is initially called immediately, then periodically every t milliseconds. A separate cancellation function is prepared using clearInterval to stop the repeated invocation when it's called after cancelTimeMs.
This implementation of the cancel function sets up an interval using setInterval. Initially, the function fn is called with the provided args. Then, every t milliseconds, the setInterval calls the function again. The clearInterval function is returned to stop further executions when called.
Time Complexity: O(1) per function call, ignoring the delay.
Space Complexity: O(1) as no additional data structures are used.
This approach uses recursive calls to setTimeout to simulate the behavior of setInterval. This gives finer control over each invocation of the function, and you can easily stop future calls by not setting further timeouts.
This code sets up a manual loop using setTimeout. The helper function callFn checks if the process is still active, invokes the function, and schedules the next invocation with setTimeout. The returned cancelFn sets the flag isActive to false, stopping further invocations.
Time Complexity: O(1) per function call, ignoring the delay.
Space Complexity: O(1) as only a boolean flag is used to manage state.
| Approach | Complexity |
|---|---|
| Approach 1: Using setInterval and clearInterval | Time Complexity: O(1) per function call, ignoring the delay. |
| Approach 2: Manual Loop with setTimeout | Time Complexity: O(1) per function call, ignoring the delay. |
How to EASILY solve LeetCode problems • NeetCode • 427,736 views views
Watch 9 more video solutions →Practice Interval Cancellation with our built-in code editor and test cases.
Practice on FleetCodePractice this problem
Open in Editor