Final Exam 02. On the Way to Annapurna

function solve(input) {
   let collection = {};

   function add(storeName, items) {
      if (!collection[storeName]) {
         collection[storeName] = [];
      }
      let currentItems = collection[storeName];
      collection[storeName] = currentItems.concat(items);
   }

   function remove(storeName) {
      if (collection[storeName]) {
         delete collection[storeName];
      }
   }

   for (let line of input) {
      if (line === 'END') {
         break;
      }
      let [command, store, otherItems] = line.split('->');
      if (command === 'Add') {
         if (otherItems.includes(',')) {
            otherItems = otherItems.split(',');
         }
         add(store, otherItems);
      } else if (command === 'Remove') {
         remove(store);
      }
   }
   console.log(`Stores list:`);
   let sorted = Object.entries(collection)
      .sort((a, b) => b[1].length - a[1].length || b[0].localeCompare(a[0]))
      .forEach(element => {
         console.log(`${element[0]}`);
         element[1].forEach(item => {
            console.log(`<<${item}>>`);
         });
      });
}