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In this approach, we use a closure to maintain the state across multiple calls to the counter function. The closure lets us keep track of the last counted value between function calls.
Time Complexity: O(1) per call.
Space Complexity: O(1) for maintaining the state.
1#include <functional>
2
std::function<int(void)> createCounter(int n) {
return [n]() mutable { return n++; };
}C++ leverages lambda expressions with a mutable keyword to allow modification of captured variables. Here, n is passed by value to the lambda, making it mutable so it can be incremented and returned each call.
This approach uses object-oriented programming to keep track of the counter's state across multiple invocations by encapsulating the state within a class instance.
Time Complexity: O(1) per call.
Space Complexity: O(1) for the instance state.
1#include <stdio.h>
2
3typedef struct {
4 int count;
5} Counter;
6
7Counter createCounter(int n) {
8 Counter c;
9 c.count = n;
10 return c;
11}
12
13int call(Counter* c) {
14 return (c->count)++;
15}In C, a structure is used to encapsulate the state. Each call to the call function requires a pointer to the structure instance to access and modify the current count.