CODEWITHSUNDEEP
arraysarraylistint
guitar99
guitar99

Reputation: 11

check to see if 3 values in array are consecutive?

I have an array, which for example contains the values 123456, which obviously contains more than 3 consecutive values.

I want a method that will return true if the array contains at least 3 consecutive values in it, thanks in advance.

for example:

972834 - return true (234)

192645 - return true (456)

etc. etc..

update! :

i have an array in java, it takes in 6 integers. for example nextTurn[], and it contains 8 4 2 5 6 5 at the moment it sorts the array - 2 4 5 5 6 8

how would i get it to return true if there are 3 consecutive numbers throughout the array?

ie so it will find 4 5 6

i would also like it to return the position of the integer in the array, so for the original array 8 4 2 5 6 5

it will return, 2 4 5 or 2 5 6

thanks for all your help guys, appreciated

Upvotes: 1

Views: 13575

Answers (4)

Dust_In_The_Wind
Dust_In_The_Wind

Reputation: 3692

Late to the party, but here's a solution.

function checkConsecutiveExists(arr) {
  for (let i = 0; i < arr.length; i++) {
    if (checkNumLast(arr, arr[i]) || checkNumMid(arr, arr[i]) || checkNumFirst(arr, arr[i])) {
      return true;
    }
  }
  return false;
}


function checkNumLast(arr, num) {
  return arr.includes(num - 2) && arr.includes(num - 1);
}

function checkNumMid(arr, num) {
  return arr.includes(num - 1) && arr.includes(num + 1);
}

function checkNumFirst(arr, num) {
  return arr.includes(num + 1) && arr.includes(num + 2);
}

console.log(checkConsecutiveExists([9, 7, 2, 8, 3, 4]));
console.log(checkConsecutiveExists([1, 9, 2, 6, 4, 50]));

It's a brute force solution, so not the most optimal.

Upvotes: 0

Guffa
Guffa

Reputation: 700302

The most straight forward solution would be to simply loop through the items, and check against the next two items:

bool HasConsecutive(int[] a){
  for(int i = 0; i < a.Length - 2; i++) {
    if (a[i + 1] == a[i] + 1 && a[i + 2] == a[i] + 2) return true;
  }
  return false;
}

Another solution is to loop through the items and count consecutive items:

bool HasConsecutive(int[] a){
  int cnt = 1;
  for (int i = 1; i < a.Length; i++) {
    if (a[i] == a[i - 1] + 1) {
      cnt++;
      if (cnt == 3) return true;
    } else {
      cnt = 1;
    }
  }
  return false;
}

Upvotes: 3

James
James

Reputation: 8586

h = new hash table
for i in array
  if  i + 1 in h && i + 2 in h
    return i, i+1, i+2
  add i to h
return no-match

Upvotes: 1

Tanner
Tanner

Reputation: 630

Should be tagged homework I'm assuming.

In pseudo code you are going to want something along the lines of

for int i = 0 to array.length - 2
    temp = array[i]
    if((array[i+1] == (temp + 1)) && (array[i+2] == (temp + 2)))
        return true
else return false

edit: This is assuming you have an array of ints. If it is a string, you are going to have to use something along the lines of charAt(position) and then convert the char to a decimal number, by subtracting '0' or using a parseInteger function

Update on the misleading part

To do this, I would create an array the same length of the string, for simplicities sake

int arr[array.length];

then loop through every item in the string array, while incrementing arr at the position the number falls at

(assuming a char array, single digit numbers) for( int i = 0; i < array.length; i++ ) arr[array[i] - '0']++;

then go through arr checking for three consecutive numbers

for( int i = 0; i < arr.length - 2; i++ )
    if( arr[i] >= 1 && arr[i+1] >= 1 && arr[i+2] >= 1 )
        return true;

return false;

Upvotes: 1

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