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The same exact solution is easily accomplished in Java, but it still relies on saving unneeded values to an array which, as has already been pointed out, is actually a less optimal solution because it needlessly stores n^2 - 2n integers in arrays. Java equivalent of this python solution:
public Solution(){
Scanner scan = new Scanner(System.in);
int n = Integer.parseInt(scan.nextLine());
int sumOne = 0;
int sumTwo = 0;
for(int currentOne = 0, currentTwo = n - 1;
currentOne < n;
currentOne ++, currentTwo--
){
String[] inputLine = scan.nextLine().split(" ");
sumOne = sumOne
+ Integer.parseInt(inputLine[currentOne]);
sumTwo = sumTwo
+ Integer.parseInt(inputLine[currentTwo]);
}
System.out.println(Math.abs(sumOne - sumTwo));
}
public static void main(String[] args) {
Solution s = new Solution();
}
I got your point, you are thinking in a very broad perspective applying it in a situation where memory is a constraint. Here it is not! Python takes 0.01 seconds to execute the above program unlike Java(0.1 - 0.29 seconds) that's why I stated it being very powerful. It is good to think in your terms where memory is getting wasted, but not here.
To your point "The same exact solution is easily accomplished in Java, but it still relies on saving unneeded values to an array which, as has already been pointed out, is actually a less optimal solution because it needlessly stores n^2 - 2n integers in arrays." Even in the below solution you are saving every input into curInput n^2 times which contradicts your point.
I'd first like to note that this discussion thread is about a Java solution, and somebody just randomly posted a Python solution in it to demonstrate that the solution could be done without nesting loops (which is not an argument that anyone was making).
Sure, Python is an easy to use and arguably powerful--I never said it wasn't; however, the use of dynamic language magic tends to make things slow, which one of the many reasons Python is generally referred to as a slow language (though improvements have been made over the last 15 years). I'm really not sure what you are using to benchmark but, though Java has a high startup cost, it will almost always execute faster than Python.
As data sets get large, memory is always a constraint; saving n^2 values to an array when only 2n are needed is not a scalable solution.
Please re-read my comment, as I did not contradict my own point at all. Saving a value from an input stream to a single register (which is an optimization any good compiler should make on this code) and then repeatedly overwriting it is not in any way the same as reading the n^2 values as a chunk, breaking the chunk down into n^2 components, storing n^2 values, and reloading and summing the 2n you actually need.
The purpose of my comment was simply to point out that the same solution is accomplishable in Java, because your comment incorrectly stated that Java couldn't read and break up a line the way that Python can and implied that is what makes Python a powerful tool. So I wrote a Java version of the Python poster's code, and pointed out why I still deem it not a good or scalable solution.
It's not quite right to say Java's performance is better than Python or viceversa, as one is better than other in different areas.
I would like to repeat the following things again -
It is good to think in your terms where memory is getting wasted, but "not here". I am a game developer and believe me I know exactly when one should be worrying about memory.
I agree to the point of yours that saving a value into a single register is better than reading n^2 values as a chunk. But, is it arguably bad? Though we have better readability, and also it is easy to code. Again, believe me it is not!
Sorry, I came 3 years later. Buy I want to poin out that the problem ask for a function that take an array.
Touching anything in main is contrary to the excercise spirit. The program have an array in some place. The excercise main is there to make a mashed input and to test the answer. In python are better solutions to test a function ( or a class or a completet lib by the way) but this is the aproach used here.
So, you can do something in the line you do. For example you can make it whit iterators that take care of reading the file until needed and storing only the numbers you need and consuming them, that would be an interesting answer, but not what the problem is about.
I like it. It was similar to mine in that there isn't a nested for loop iterating over multi dimensional array. My solution is unfortunately more pedantic and incurs looping twice.
Great approach! Just a quick comment. You can take differences of left and right terms as you import each row. This computes a cumulative difference. There is no need to compute the sums first and then take differences. It's a bit simpler and, hopefully, faster ;)
This is a solution where we go through the matrix only once, no arrays just check if we add the number to one of the diagonals or both.
publicstaticvoidmain(String[]args){Scannerin=newScanner(System.in);intN=in.nextInt();intsumA=0,sumB=0;intM=N*N;//counter for first diagonalintcountA=N-N;// 0 -> N*N ; step N+1 // counte for second diagonalintcountB=N-1;// N-1 -> N*N-N; step N-1 intcountBLimit=M-1;// the last element is not for this diagonal for(inti=0;i<M;i++){intk=in.nextInt();if(i==countA){sumA+=k;countA+=N+1;}if(i==countB&&countB<countBLimit){sumB+=k;countB+=N-1;}}System.out.println(Math.abs(sumA-sumB));}
Diagonal Difference
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The same exact solution is easily accomplished in Java, but it still relies on saving unneeded values to an array which, as has already been pointed out, is actually a less optimal solution because it needlessly stores n^2 - 2n integers in arrays. Java equivalent of this python solution:
I got your point, you are thinking in a very broad perspective applying it in a situation where memory is a constraint. Here it is not! Python takes 0.01 seconds to execute the above program unlike Java(0.1 - 0.29 seconds) that's why I stated it being very powerful. It is good to think in your terms where memory is getting wasted, but not here.
To your point "The same exact solution is easily accomplished in Java, but it still relies on saving unneeded values to an array which, as has already been pointed out, is actually a less optimal solution because it needlessly stores n^2 - 2n integers in arrays." Even in the below solution you are saving every input into curInput n^2 times which contradicts your point.
Yours Java equivalent solution to Python looks so hard to read.
Look at this Python solution:
Simple and Powerful!
We need to learn and understand the balance required between performance and memory usage.
I'd first like to note that this discussion thread is about a Java solution, and somebody just randomly posted a Python solution in it to demonstrate that the solution could be done without nesting loops (which is not an argument that anyone was making).
It's not quite right to say Java's performance is better than Python or viceversa, as one is better than other in different areas. I would like to repeat the following things again -
Sorry, I came 3 years later. Buy I want to poin out that the problem ask for a function that take an array.
Touching anything in main is contrary to the excercise spirit. The program have an array in some place. The excercise main is there to make a mashed input and to test the answer. In python are better solutions to test a function ( or a class or a completet lib by the way) but this is the aproach used here.
So, you can do something in the line you do. For example you can make it whit iterators that take care of reading the file until needed and storing only the numbers you need and consuming them, that would be an interesting answer, but not what the problem is about.
neither my code , nor yours is printing, please point the error
try this
Here is a python 3 version below:
plz explain
Actually the above solution was not working for me, so I did the solution without taking the input as it was already described in the main function.
hi i am a beginner in python can anyone explain me , how have they input 2D list in Python from the user ....
for a_i in range(n): a_t = [int(a_temp) for a_temp in input().strip().split(' ')] a.append(a_t)
That python code was brilliant
hi Allison, below is my solution. Can you please provide your feedback.
I like it. It was similar to mine in that there isn't a nested for loop iterating over multi dimensional array. My solution is unfortunately more pedantic and incurs looping twice.
very elegant solution, mine was similar:
You are great
Great approach! Just a quick comment. You can take differences of left and right terms as you import each row. This computes a cumulative difference. There is no need to compute the sums first and then take differences. It's a bit simpler and, hopefully, faster ;)
since i am a beginner will you please tell me what is the function of .split ?
Let's say you have "1,2,3,hello" and you call .split(","). This will give you back an array of ["1", "2", "3", "hello"].
This is a solution where we go through the matrix only once, no arrays just check if we add the number to one of the diagonals or both.
Thnx a lot
what is the need to parse the value to integer?