Write a function expect that helps developers test their code. It should take in any value val and return an object with the following two functions.
toBe(val) accepts another value and returns true if the two values === each other. If they are not equal, it should throw an error "Not Equal".notToBe(val) accepts another value and returns true if the two values !== each other. If they are equal, it should throw an error "Equal".Example 1:
Input: func = () => expect(5).toBe(5)
Output: {"value": true}
Explanation: 5 === 5 so this expression returns true.
Example 2:
Input: func = () => expect(5).toBe(null)
Output: {"error": "Not Equal"}
Explanation: 5 !== null so this expression throw the error "Not Equal".
Example 3:
Input: func = () => expect(5).notToBe(null)
Output: {"value": true}
Explanation: 5 !== null so this expression returns true.
The key to solving #2704 To Be Or Not To Be is to carefully analyze the condition described in the problem and determine the correct output based on the given input. Since this is an Easy level problem under the General category, the task typically involves evaluating a simple rule, comparison, or transformation.
A common approach is to iterate through the input (such as a string, list, or set of values) and apply conditional checks using basic control flow like if statements. While processing the input, track the required information and decide which output should be returned according to the problem’s rules. The solution usually requires a single pass over the data.
Because the logic is straightforward and does not require complex data structures, the overall complexity is efficient. Most implementations run in O(n) time where n represents the size of the input, while the space complexity remains minimal.
| Approach | Time Complexity | Space Complexity |
|---|---|---|
| Single Pass Conditional Evaluation | O(n) | O(1) |
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The closure-based approach makes use of JavaScript's closure capabilities to encapsulate the comparison logic within the returned object. The main idea here is to utilize closures to maintain the original value passed to the expect function, and then provide methods that perform the respective comparisons. This approach leverages the benefits of closures to maintain a clean and functional interface.
Time Complexity: O(1) for both toBe and notToBe methods as they perform constant time operations.
Space Complexity: O(1) since the space required does not grow with the size of the input.
1function expect(val) {
2 return {
3 toBe: function(value) {
4 if (val === value) {
5 return true;
6 } else {
7 throw new Error('Not Equal');
8 }
9 },
10 notToBe: function(value) {
11 if (val !== value) {
12 return true;
13 } else {
14 throw new Error('Equal');
15 }
16 }
17 };
18}
19In JavaScript, the expect function returns an object with two methods: toBe and notToBe. These methods use closures to access the value originally passed into expect. When toBe is called, it checks if the values are strictly equal and returns true or throws an error appropriately. Similarly, notToBe checks for inequality and handles it in the same manner. The use of closures allows these methods to always reference the correct original val that expect was called with.
The class-based approach in languages like C++, C#, and Java exploits object-oriented programming features to achieve encapsulation and method binding. Here, the idea is to define a class that keeps track of the initial value and provides methods that can be invoked on it to perform the required checks. This method is beneficial for languages where closures don't exist or are cumbersome to implement, maintaining a clear object-oriented design.
Time Complexity: O(1) for both methods.
Space Complexity: O(1).
1#include <stdexcept>
2
3class Expect {
4public:
Expect(int val) : val_(val) {}
bool toBe(int value) {
if (val_ == value) {
return true;
}
throw std::runtime_error("Not Equal");
}
bool notToBe(int value) {
if (val_ != value) {
return true;
}
throw std::runtime_error("Equal");
}
private:
int val_;
};
// Usage:
// Expect(5).toBe(5);
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Problems with similar logic and difficulty often appear in early screening rounds or practice sets. While the exact problem may vary, the underlying concepts of conditional evaluation and simple iteration are commonly tested in technical interviews.
Most solutions rely on basic data types such as strings, arrays, or simple variables. Since the problem is categorized as Easy, complex data structures are typically unnecessary unless the input format specifically requires them.
The optimal approach is usually to process the input once and evaluate the required condition using simple control flow. By applying direct comparisons or checks during a single traversal, the problem can typically be solved in linear time with constant extra space.
Focus on understanding the problem statement clearly and identifying the exact condition that determines the output. Implement the logic using simple conditional checks and ensure edge cases such as empty input or boundary values are handled correctly.
In C++, the Expect class is used to encapsulate the initial value. The constructor initializes this value and the methods toBe and notToBe perform the comparisons. If conditions are not satisfied, they throw runtime errors. This class-based approach leverages C++'s support for OOP to provide a straightforward implementation.