Match pattern with array

Match pattern with array.markdown

Match pattern with array

A Pen by Cheng Ly on CodePen.

License.

script.js

/**
 * Match pattern!
 *
 * Given a pattern (array) and an array of strings, see if the pattern exist in array
 * pattern: ['a', 'b', 'a'], test: ['cat', 'dog', 'cat'] => true
 * pattern: ['a', 'b', 'a'], test: ['cat', 'dog', 'cat', 'cat'] => true
 * pattern: ['a', 'b', 'a'], test: ['cat', 'dog', 'bear'] => false
 *
 */


// Pseudocode
//
// loop through pattern
//   if pattern[i] doesn't exist in hash table, 
//      store value of Test[i] in hash w/ key being pattern[i]
//   else 
//      check if test[i] = pattern[i]
//         if doesn't match
//            return false
// return true


// Using for-loop
function testPattern1(pattern, test) {
  var store = {};
  
  for (let i = 0; i < pattern.length; i++) {
    if (store[pattern[i]] && store[pattern[i]] !== test[i]) return false;
    store[pattern[i]] = test[i];
  }
  
  return true;
}

// Using forEach
function testPattern2(pattern, test) {
  var store = {};
  var result = true;
  
  pattern.forEach((val, i) => {
    if (store[val] && store[val] !== test[i]) {
      result = false;
      return;
    }
    store[val] = test[i];
  });
  
  return result;
}


// Test
var pattern = ['a', 'b', 'a'], 
    test1 = ['cat', 'dog', 'cat'],
    test2 = ['cat', 'dog', 'cat', 'cat'],
    test3 = ['cat', 'dog', 'bear'];

// for-loop
console.log('for-loop ----------------------------->')
console.log(testPattern1(pattern, test1)); // true
console.log(testPattern1(pattern, test2)); // true
console.log(testPattern1(pattern, test3)); // false

// forEach
console.log('forEach ----------------------------->')
console.log(testPattern2(pattern, test1)); // true
console.log(testPattern2(pattern, test2)); // true
console.log(testPattern2(pattern, test3)); // false