Algorithm correctness for Bank Kattis problem

<a href="https://open.kattis.com/problems/bank" target="_blank">This</a>&nbsp;is the problem I am referring to. In quick summary:

This is the problem I am referring to. In quick summary:

Input: An integer time T; the time in minutes in which a bank closes and a set of pairs c and t that denotes the amount of cash (integer) this person carries and the time in minutes from now after which person leaves if not served. It takes one minute to serve a person and you must begin serving a person at time t at the latest.

Output: Maximum amount of money that can be collected within closing time.

My approach was this: place all the people in a map that maps money to time. I sort this map by money. I then make a queue-like structure where I take the person with the most money and place him/her as far back as possible. If the spot is occupied, then I move forward until I find a spot. If I can't then I just don't add the person.

Below is my helper function to determine whether or not I can insert a person.

// returns index where we can insert, otherwise -1
int canInsert(bool* queue, int timeToInsert) {
    if (!queue[timeToInsert]) {
        return timeToInsert;
    } else {
        int index = timeToInsert-1;
        while (index >= 0) {
            if (!queue[index]) {
                return index;
            } else {
                index--;
            }
        }
        return -1;
    }
}

Here is the main driver function:

// moneyToTime is a map that maps a person's money to the time value
int Bank(int T, map<int, int> moneyToTime) {
    int answer = 0;
    bool queue[47] = {0};
    for (map<int,int>::reverse_iterator i = moneyToTime.rbegin(); i != moneyToTime.rend(); i++) {
        if (T > 0) {
            // try to insert. If we can, then add to sum. Otherwise, don't.
            int potentialIndex = canInsert(queue, i->second);
            if (potentialIndex != -1) {
                queue[potentialIndex] = 1;
                answer += i->first;
                T--;
            }
        } else {
            break;
        }
    }
    return answer;
}

Logically, this makes sense to me and it is passing almost all the test cases. There are a couple that are failing; I can not see what they are. The test case errors are in fact indicating wrong answer, as opposed to bad runtime errors. Can someone help me see the fallacy in my approach?

C/C++ vs. Rust: A developer’s perspective

C/C++ vs. Rust: A developer’s perspective

In this post, you'll see the difference between Rust and C/C++ in a developer’s perspective

Originally published by Maourice Gonzalez at https://www.onmsft.com

C++ is an incredibly fast and efficient programming language. Its versatility knows no bounds and its maturity ensures support and reliability are second to none. Code developed in C++ is also extremely portable, all major operating systems support it. Many developers begin their coding journey with the language, and this is no coincidence. Being object-oriented means it does a very good job of teaching concepts like classes, inheritance, abstraction, encapsulation and polymorphism. Its concepts and syntax can be found in modern languages like C#, Java and Rust. It provides a great foundation that serves as a high speed on ramp to the more popular, easier to use and modern alternatives.

Now it’s not all rosy. C++ has a very steep learning curve and requires developers to apply best practices to the letter or risk ending up with unsafe and/or poor performing code. The small footprint of the standard library, while most times considered a benefit, also adds to the level of difficulty. This means successfully using C++ to create useful complex libraries and applications can be challenging. There is also very little offered in terms of memory management, developers must do this themselves. Novice programmers could end up with debugging nightmares as their lack of experience leads to memory corruption and other sticky situations. This last point has lead many companies to explore fast performing, safe and equally powerful alternatives to C++. For today’s Microsoft that means Rust.

The majority of vulnerabilities fixed and with a CVE [Common Vulnerabilities and Exposures] assigned are caused by developers inadvertently inserting memory corruption bugs into their C and C++ code - Gavin Thomas, Microsoft Security Response Center

Rust began as a personal project by a Mozilla employee named Graydon Hoare sometime in 2006. This ambitious project was in pre-release development for almost a decade, finally launching version 1.0 in May 2015. In what seems to be the blink of an eye it has stolen the hearts of hordes of developers going as far as being voted the most loved language four years straight since 2016 in the Stack Overflow Developer Survey.

The hard work has definitely paid off. The end result is very efficient language which is characteristically object oriented. The fact that it was designed to be syntactically similar to C++ makes it very easy to approach. But unlike the aforementioned it was also designed to be memory safe while also employing a form of memory management without the explicit use of garbage collection.

The ugly truth is software development is very much a trial and error endeavor. With that said Rust has gone above and beyond to help us debug our code. The compiler produces extremely intuitive and user friendly error messages along with great direct linking to relevant documentation to aid with troubleshooting. This means if the problem is not evident, most times the answer is a click away. I’ve found myself rarely having to fire up my browser to look for solutions outside of what the Rust compiler offers in terms of explanation and documentation.

Rust does not have a garbage collector but most times still allocates and release memory for you. It’s also designed to be memory safe, unlike C++ which very easily lets you get into trouble with dangling pointers and data races. In contrast Rust employs concepts which help you prevent and avoid such issues.

There are many other factors which have steered me away from C++ and onto Rust. But to be honest it has nothing to do with all the great stuff we’ve just explored. I came to Rust on a journey that began with WebAssembly. What started with me looking for a more efficient alternative to JavaScript for the web turned into figuring out just how powerful Rust turns out to be. From its seamless interop…

Automatically generate binding code between Rust, WebAssembly, and JavaScript APIs. Take advantage of libraries like web-sys that provide pre-packaged bindings for the entire web platform. – Rust website

To how fast and predictable its performance is. Everything in our lives evolves. Our smartphones, our cars, our home appliances, our own bodies. C++ while still incredibly powerful, fast and versatile can only take us so far. There is no harm in exploring alternatives, especially one as exceptional and with as much promise as Rust.

What do you guys think? Have you or would you give Rust a try? Let us know your thoughts in the comments section below.

Thanks for reading

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Further reading

Why you should move from Node.js to Rust in 2019

Rust Vs. Haskell: Which Language is Best for API Design?

7 reasons why you should learn Rust programming language in 2019

An introduction to Web Development with Rust for Node.js Developers

Efficient one algorithm of these two algorithms

Both of these algorithms are giving same output but the first one takes nearly double time (&gt;.67) compared to second one (.36). How is this possible? Can you tell me the time complexity of both algorithms? If they're the same, why is the time different?

Both of these algorithms are giving same output but the first one takes nearly double time (>.67) compared to second one (.36). How is this possible? Can you tell me the time complexity of both algorithms? If they're the same, why is the time different?

1st algorithm:

 for (int i =0 ;i<n;i++){
        cin>>p[i];
        if(i>0){
            if(p[i-1]>p[i]){
                cout<<p[i]<<" ";
            }
            else{
                cout<<"-1"<<" ";
            }
        }
    }

2nd algorithm:

for (int i =0 ;i<n;i++){
        cin>>p[i];
}
for (int i =0 ; i&lt;n-1;i++){
   if(p[i]&gt;p[i+1]){
            cout&lt;&lt;p[i]&lt;&lt;" ";
        }
        else{
            cout&lt;&lt;"-1"&lt;&lt;" ";
        } 
}