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Thread: Logic to find adjacency of numbers 0 & 1 in an array

1. Logic to find adjacency of numbers 0 & 1 in an array

[redacted]

I should mention here that number of elements can be from 1....10'000. And it has to be done as O(N)

I attempted at the problem like so,

```public static int adjacencies(int[] A) {
int count = 0;
boolean found = false;

for(int i = 0; i < A.length-1; i++) {
if (A[i] == A[i+1]) {
System.out.println(A[i] + " " + A[i+1]);
count++;
}
else if (((i + 2) <  A.length-1) && !found) {
if ((A[i] == 0 && A[i+1] == 1 && A[i+2] == 0) || (A[i] == 1 && A[i+1] == 0 && A[i+2] == 1)) {
found = true;
count = count + 2;
}
else if ((A[i] == 1 && A[i+1] == 0 && A[i+2] == 0) || (A[i] == 0 && A[i+1] == 1 && A[i+2] == 1)) {
found = true;
count = count + 1;
}
}
}

return count;
}

public static void main (String[] args) {
int[] A = new int[] {1,1,0,1,0,0};
System.out.println(A);
System.out.println("Count: " + count);
}```

To me it looks right and it seems to work. Can someone find a better way of doing this instead of this clunky way ?

2. Re: Logic to find adjacency of numbers 0 & 1 in an array

If all you are doing for now is count adjacent coins then use a for loop and a single if statement.
```for each coin (except the last one) {
if current coin equals next coin {
increase count
}
}```
Determining which coin to flip is a bit more complicated. You would start by find the longest sequence of coins that are the same.

3. Re: Logic to find adjacency of numbers 0 & 1 in an array

```public static int adjacencies(int[] A) {
int count = 0;
boolean found = false;
int m=0;
for(int i = 1; i < A.length; i++) {
if (A[i] == A[i-1])
count++;
else if (!found){
m= (i < A.length-1)?2:1);
found=true;
}
}
return count+m;
}```

4. Re: Logic to find adjacency of numbers 0 & 1 in an array

Originally Posted by kasun.tawlatta
[redacted]

I should mention here that number of elements can be from 1....10'000. And it has to be done as O(N)

I attempted at the problem like so,

```public static int adjacencies(int[] A) {
int count = 0;
boolean found = false;

for(int i = 0; i < A.length-1; i++) {
if (A[i] == A[i+1]) {
System.out.println(A[i] + " " + A[i+1]);
count++;
}
else if (((i + 2) <  A.length-1) && !found) {
if ((A[i] == 0 && A[i+1] == 1 && A[i+2] == 0) || (A[i] == 1 && A[i+1] == 0 && A[i+2] == 1)) {
found = true;
count = count + 2;
}
else if ((A[i] == 1 && A[i+1] == 0 && A[i+2] == 0) || (A[i] == 0 && A[i+1] == 1 && A[i+2] == 1)) {
found = true;
count = count + 1;
}
}
}

return count;
}

public static void main (String[] args) {
int[] A = new int[] {1,1,0,1,0,0};
System.out.println(A);
System.out.println("Count: " + count);
}```

To me it looks right and it seems to work. Can someone find a better way of doing this instead of this clunky way ?
I guess, the logic provided doesn't cover all cases.
Check with the following input: {1,0,0,0,0,1,0,1}

5. Re: Logic to find adjacency of numbers 0 & 1 in an array

@kaizen

Please do not dig up old threads. If they are more than three months old let them
die so to speak.