linearIn challenge

gudii9
gudii9 used Ask the Experts™
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Hi,

I am working on below challenge

Array-3 > linearIn
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Given two arrays of ints sorted in increasing order, outer and inner, return true if all of the numbers in inner appear in outer. The best solution makes only a single "linear" pass of both arrays, taking advantage of the fact that both arrays are already in sorted order.

linearIn([1, 2, 4, 6], [2, 4]) → true
linearIn([1, 2, 4, 6], [2, 3, 4]) → false
linearIn([1, 2, 4, 4, 6], [2, 4]) → true

how to verify one array has one other target array or not? is there is built in method for that?
please advise
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Gerwin Jansen, EE MVETopic Advisor
Most Valuable Expert 2016

Commented:
The arrays are sorted - you just go over them and compare the numbers.

Author

Commented:
i will try. so two for loops needed right for each array?
Gerwin Jansen, EE MVETopic Advisor
Most Valuable Expert 2016

Commented:
Yes
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Author

Commented:

Author

Commented:
psedo code

1. convert inner array to list
2. convert outer array to list
3. check whether outer contains inner list.
4. if yes return true
5.if false return false

public boolean linearIn(int[] outer, int[] inner) {
  List o=Arrays.asList(outer);
    List i=Arrays.asList(inner);
    if(o.contains(i)){
      return true;
    }
    else return false;
}

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\i tried as above failing some tests. please advise
Expected      Run            
linearIn([1, 2, 4, 6], [2, 4]) → true      false      X      
linearIn([1, 2, 4, 6], [2, 3, 4]) → false      false      OK      
linearIn([1, 2, 4, 4, 6], [2, 4]) → true      false      X      
linearIn([2, 2, 4, 4, 6, 6], [2, 4]) → true      false      X      
linearIn([2, 2, 2, 2, 2], [2, 2]) → true      false      X      
linearIn([2, 2, 2, 2, 2], [2, 4]) → false      false      OK      
linearIn([2, 2, 2, 2, 4], [2, 4]) → true      false      X      
linearIn([1, 2, 3], [2]) → true      false      X      
linearIn([1, 2, 3], [-1]) → false      false      OK      
linearIn([1, 2, 3], []) → true      false      X      
linearIn([-1, 0, 3, 3, 3, 10, 12], [-1, 0, 3, 12]) → true      false      X      
linearIn([-1, 0, 3, 3, 3, 10, 12], [0, 3, 12, 14]) → false      false      OK      
linearIn([-1, 0, 3, 3, 3, 10, 12], [-1, 10, 11]) → false      false      OK      
other tests
X      
Your progress graph for this problem

Author

Commented:
import java.util.Arrays;
import java.util.List;

public class LinearIn {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		int[] outer = { 1, 2, 4, 6 };
		int[] inner = { 2, 4 };
		System.out.println("is-->" + linearIn(outer, inner));
	}

	public static boolean linearIn(int[] outer, int[] inner) {
		List o = Arrays.asList(outer);
		List i = Arrays.asList(inner);
		if (o.containsAll(i)) {
			return true;
		} else
			return false;
	}

}

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is-->false

changed contains to containsAll still getting false instead of true
Topic Advisor
Most Valuable Expert 2016
Commented:
I would just start with the shortest array and try to find values in the longest array, increase indexes as needed. When you reach the end you have either true or false.

Author

Commented:
public boolean linearIn(int[] outer, int[] inner) {
		int match=0;
		int x=0;
		if(inner.length==0){
			return true;
		}
		
		 for (int i = 0; i < outer.length; i++) {
			 
			 
			 if(outer[i]==inner[x]){
				 match++;
				 x++;
			 }
			 else if(outer[i]>inner[x]){
				 return false;
			 }
			 else if(outer[i]< inner[x]){
				 return false;
			 }
			 if(match==inner.length){
				 return true;
			 }
			
		}
		 return false;
		}

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Expected      Run            
linearIn([1, 2, 4, 6], [2, 4]) → true      false      X      
linearIn([1, 2, 4, 6], [2, 3, 4]) → false      false      OK      
linearIn([1, 2, 4, 4, 6], [2, 4]) → true      false      X      
linearIn([2, 2, 4, 4, 6, 6], [2, 4]) → true      false      X      
linearIn([2, 2, 2, 2, 2], [2, 2]) → true      true      OK      
linearIn([2, 2, 2, 2, 2], [2, 4]) → false      false      OK      
linearIn([2, 2, 2, 2, 4], [2, 4]) → true      false      X      
linearIn([1, 2, 3], [2]) → true      false      X      
linearIn([1, 2, 3], [-1]) → false      false      OK      
linearIn([1, 2, 3], []) → true      true      OK      
linearIn([-1, 0, 3, 3, 3, 10, 12], [-1, 0, 3, 12]) → true      false      X      
linearIn([-1, 0, 3, 3, 3, 10, 12], [0, 3, 12, 14]) → false      false      OK      
linearIn([-1, 0, 3, 3, 3, 10, 12], [-1, 10, 11]) → false      false      OK      
other tests
X
tried as above failing some tests. please advise

package com.upcast;

public class LinearIn {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		int[] outer={1,2,4,6};
		int[] inner={2,4};
		System.out.println("linearIn is===>"+linearIn(outer,inner));

	}
	public static boolean linearIn(int[] outer, int[] inner) {
		int match=0;
		int x=0;
		if(inner.length==0){
			return true;
		}
		
		 for (int i = 0; i < outer.length; i++) {
			 
			 
			 if(outer[i]==inner[x]){
				 match++;
				 x++;
			 }
			 else if(outer[i]>inner[x]){
				 return false;
			 }
			 else if(outer[i]< inner[x]){
				 return false;
			 }
			 if(match==inner.length){
				 return true;
			 }
			
		}
		 return false;
		}

}

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linearIn is===>false

Commented:
You should take Gerwin Jansen advice in his last comment above here.
I would just start with the shortest array ...
 Also debug statements would help here too.

Author

Commented:
public boolean linearIn(int[] outer, int[] inner) {
		int match=0;
		int x=0;
		if(inner.length==0){
			return true;
		}
		
		 for (int i = 0; i < outer.length; i++) {
			 
			 
			 if(outer[i]==inner[x]){
				 match++;
				 x++;
			 }
			 else if(outer[i]>inner[x]){
				 return false;
			 }
			/* else if(outer[i]< inner[x]){
				 return false;
			 }*/
			 if(match==inner.length){
				 return true;
			 }
			
		}
		 return false;
		}

Open in new window


Expected      Run            
linearIn([1, 2, 4, 6], [2, 4]) → true      true      OK      
linearIn([1, 2, 4, 6], [2, 3, 4]) → false      false      OK      
linearIn([1, 2, 4, 4, 6], [2, 4]) → true      true      OK      
linearIn([2, 2, 4, 4, 6, 6], [2, 4]) → true      true      OK      
linearIn([2, 2, 2, 2, 2], [2, 2]) → true      true      OK      
linearIn([2, 2, 2, 2, 2], [2, 4]) → false      false      OK      
linearIn([2, 2, 2, 2, 4], [2, 4]) → true      true      OK      
linearIn([1, 2, 3], [2]) → true      true      OK      
linearIn([1, 2, 3], [-1]) → false      false      OK      
linearIn([1, 2, 3], []) → true      true      OK      
linearIn([-1, 0, 3, 3, 3, 10, 12], [-1, 0, 3, 12]) → true      true      OK      
linearIn([-1, 0, 3, 3, 3, 10, 12], [0, 3, 12, 14]) → false      false      OK      
linearIn([-1, 0, 3, 3, 3, 10, 12], [-1, 10, 11]) → false      false      OK      
other tests
OK      
package com.upcast;

public class LinearIn {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		int[] outer={1,2,4,6};
		int[] inner={2,4};
		System.out.println("linearIn is===>"+linearIn(outer,inner));

	}
	public static boolean linearIn(int[] outer, int[] inner) {
		int match=0;
		int x=0;
		if(inner.length==0){
			return true;
		}
		
		 for (int i = 0; i < outer.length; i++) {
			 
			 
			 if(outer[i]==inner[x]){
				 match++;
				 x++;
			 }
			 else if(outer[i]>inner[x]){
				 return false;
			 }
			/* else if(outer[i]< inner[x]){
				 return false;
			 }*/
			 if(match==inner.length){
				 return true;
			 }
			
		}
		 return false;
		}

}

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linearIn is===>true

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when i comment last else if it passes all tests.

Not clear how and why?

Commented:
Not clear how and why?
What was the purpose of
29:			/* else if(outer[i]< inner[x]){
30:				 return false;
31:			 }*/

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Please tell us what you were thinking when you wrote that .  
Anyway, your code looks good.  Here is mine.
public boolean linearIn(int[] outer, int[] inner) {
    boolean found = false;
    int j = 0;
    for(int i = 0; i < inner.length; i++){
        for(int k = j; k < outer.length; k++){
          if(inner[i] == outer[k]){
            j = k;
            found = true;
            break;
          } 
        }
        if(!found)return false;
        found = false;
    }
   return true;
}

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I don't know which is better.

Author

Commented:
i was thinking there are 3 cases always right when comparing
1. equals
2. greater
3. less than

Commented:
We search for when values match.
Why do you care if the values are greater or less than?

Author

Commented:
public boolean linearIn(int[] outer, int[] inner) {
		int match=0;
		int x=0;
		if(inner.length==0){
			return true;
		}
		
		 for (int i = 0; i < outer.length; i++) {
			 
			 
			 if(outer[i]==inner[x]){
				 match++;
				 x++;
			 }
			 /*else if(outer[i]>inner[x]){
				 return false;
			 }*/
			/* else if(outer[i]< inner[x]){
				 return false;
			 }*/
			 if(match==inner.length){
				 return true;
			 }
			
		}
		 return false;
		}

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actually i could comment other else if still fine as i need to worry only about == case

public boolean linearIn(int[] outer, int[] inner) {
		int match=0;
		int x=0;
		if(inner.length==0){
			return true;
		}
		
		 for (int i = 0; i < outer.length; i++) {
			 
			 
			 if(outer[i]==inner[x]){
				 match++;
				 x++;
			 }
			 /*else if(outer[i]>inner[x]){
				 return false;
			 }*/
			/* else if(outer[i]< inner[x]){
				 return false;
			 }*/
			 if(match==inner.length){
				 return true;
			 }
			
		}
		 return false;
		}

Open in new window

Expected      Run            
linearIn([1, 2, 4, 6], [2, 4]) → true      true      OK      
linearIn([1, 2, 4, 6], [2, 3, 4]) → false      false      OK      
linearIn([1, 2, 4, 4, 6], [2, 4]) → true      true      OK      
linearIn([2, 2, 4, 4, 6, 6], [2, 4]) → true      true      OK      
linearIn([2, 2, 2, 2, 2], [2, 2]) → true      true      OK      
linearIn([2, 2, 2, 2, 2], [2, 4]) → false      false      OK      
linearIn([2, 2, 2, 2, 4], [2, 4]) → true      true      OK      
linearIn([1, 2, 3], [2]) → true      true      OK      
linearIn([1, 2, 3], [-1]) → false      false      OK      
linearIn([1, 2, 3], []) → true      true      OK      
linearIn([-1, 0, 3, 3, 3, 10, 12], [-1, 0, 3, 12]) → true      true      OK      
linearIn([-1, 0, 3, 3, 3, 10, 12], [0, 3, 12, 14]) → false      false      OK      
linearIn([-1, 0, 3, 3, 3, 10, 12], [-1, 10, 11]) → false      false      OK      
other tests
OK      
package com.upcast;

public class LinearIn {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		int[] outer={1,2,4,6};
		int[] inner={2,4};
		System.out.println("linearIn is===>"+linearIn(outer,inner));

	}
	public static boolean linearIn(int[] outer, int[] inner) {
		int match=0;
		int x=0;
		if(inner.length==0){
			return true;
		}
		
		 for (int i = 0; i < outer.length; i++) {
			 
			 
			 if(outer[i]==inner[x]){
				 match++;
				 x++;
			 }
			/* else if(outer[i]>inner[x]){
				 return false;
			 }*/
			/* else if(outer[i]< inner[x]){
				 return false;
			 }*/
			 if(match==inner.length){
				 return true;
			 }
			
		}
		 return false;
		}

}

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linearIn is===>true

above also passes all tests

Author

Commented:
package com.upcast;

public class LinearIn {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		int[] outer={1,2,4,6};
		int[] inner={2,4};
		System.out.println("linearIn is===>"+linearIn(outer,inner));

	}
	public static boolean linearIn(int[] outer, int[] inner) {
		int match=0;
		int x=0;
		if(inner.length==0){
			return true;
		}
		
		 for (int i = 0; i < outer.length; i++) {
			 
			 
			 if(outer[i]==inner[x]){
				 match++;
				 x++;
			 }
			/* else if(outer[i]>inner[x]){
				 return false;
			 }*/
			else if(outer[i]< inner[x]){
				 return false;
			 }
			 if(match==inner.length){
				 return true;
			 }
			
		}
		 return false;
		}

}

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if i keep less than else if while debugging it is going to that loop wrongly. not sure why?
ElseIf.png

Author

Commented:
We search for when values match.
Why do you care if the values are greater or less than?

true.

i will close this

Author

Commented:
one other thing

public boolean linearIn(int[] outer, int[] inner) {
  List o=Arrays.asList(outer);
    List i=Arrays.asList(inner);
    if(o.contains(i)){
      return true;
    }
    else return false;
}

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why above wont work? how tweak to make above collection list approach work?

Commented:
above collection list approach work?

I don't think it will work for all cases.  For instance , this case from codingBat tests
linearIn([-1, 0, 3, 3, 3, 10, 12], [-1, 0, 3, 12]) → true
the values of the second array are spread out. Where a List would require them to be sequential (next to each other).  
I don't know why it didn't work for the easier cases(where the elements were sequential ).

Author

Commented:
so instead of list use some other collection object which can work with spread out elements?

Commented:
Yes, theoretically  your idea should work with Sets.  If I find time, I will try to find a solution.

Author

Commented:
package com.upcast;

import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;

public class LinearIn {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		int[] outer={1,2,4,6};
		int[] inner={2,3,4};
		System.out.println("linearIn is===>"+linearIn(outer,inner));

	}
	public static boolean linearIn(int[] outer, int[] inner) {
		
		//public boolean linearIn(int[] outer, int[] inner) {
			 // List o=Arrays.asList(outer);
			 //   List i=Arrays.asList(inner);
			    Set<Integer> set1 = new HashSet<Integer>(Arrays.asList(outer));
			    Set<Integer> set2 = new HashSet<Integer>(Arrays.asList(inner));
			    if(set1.contains(set2)){
			      return true;
			    }
			    else return false;
			//}
	}

}

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above gives compilation error at line 21 and 22
says

The constructor HashSet<Integer>(Arrays.asList(outer)) is undefined

Commented:
I tried to find a solution using List or Set. But, I couldn't do it.
Commented:
I finally found a solution.  
public boolean linearIn(int[] outer, int[] inner) {
		Set<Integer> outerSet = new HashSet<Integer>();
		Set<Integer> innerSet = new HashSet<Integer>();
		for(int i = 0; i < outer.length; i++){
			outerSet.add(outer[i]);
		}
		for(int j = 0; j < inner.length; j++){
			innerSet.add(inner[j]);
		}
		return outerSet.containsAll(innerSet);
}

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