Increasing decrease sequence

#1

Take the following as input.

A number (N)
Take N more numerical inputs
The N inputs for a sequence S = s1, s2, …, sN. Compute if it is possible to split sequence into two sequences -
s1 to si and si+1 to sN such that first sequence is strictly decreasing and second is strictly increasing. Print true/false as output.

public static boolean valid_invalid(int n){

    int prev = scn.nextInt();
    int cnt = 1;
    boolean goingUp = false;
    boolean isValid = true;

    while(cnt < n){

        int curr = scn.nextInt();

        int diff = curr - prev;
         // As the sequence must be strctly decreasing or increasing
        if(diff == 0){  
            isValid = false;
        }else if(diff > 0){  // If Sequence is increasing 
            goingUp = true;
        }else if(goingUp && diff < 0){
          // If Sequence is Decreasing if its already increased once
                            isValid = false;
        }

        prev = curr;
        cnt++;

    }

    return isValid;

}
sir i think the above solution to this problem is not in c++. can u give it in c++ language with explaination.

#2

Hello @Sheenagoyal21,

In the above question, you have to consider following:

  1. strictly increasing eg: 5 1 2 3 4 5
  2. strictly decreasing eg: 5 5 4 3 2 1
  3. strictly decreasing then strictly increasing eg: 3 2 1 2 3
  4. strictly increasing then strictly decreasing eg: 1 2 3 2 1

for 1., 2., 3. case you should print true and
for case 4. and rest, it should print false.
Note: strictly words means equal numbers at adjacent positions would not be accepted. eg: 5 3 2 2 1 0

I am here to help you in understanding the logic.
Thus, i would suggest you to implement above mentioned cases and send your code if you face any issue.
I would help you in resolving the error if any occurs.

Here is the required code. But i would insist you to try it yourself first.
By looking at the answer without trying really hard, wont build any logic.

Hope, you are getting what i said.
Give a like, if you are satisfied.

4 Likes
#3

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#4

My code is passing all the test cases, just not the test case 0. I don’t understand the issue. Please help.

import java.util.*;
public class Main {
public static void main(String args[]) {

	Scanner s = new Scanner(System.in);

	int n = s.nextInt(); // 5

	int previous = s.nextInt(); // 1
	boolean value = true;

	for(int i = 1; i <= n -1 ; i++)
	{
		int current = s.nextInt(); // 2,3,4,5 or 2,3,1,0
		
		if(current == previous) 
		{
			value = false;
		}
		else if(current > previous)
		{
			value = true;
		}
		else if(current < previous || current < 0)
		value = false;

		previous = current; // 2, 
	}

	if(value == true)
	{
		System.out.println(value);
	}
	else
	System.out.println(value);
}

}