1431. Kids With the Greatest Number of Candies

Given the array candies and the integer extraCandies, where candies[i] represents the number of candies that the ith kid has.
For each kid check if there is a way to distribute extraCandies among the kids such that he or she can have the greatest number of candies among them. Notice that multiple kids can have the greatest number of candies.

• Example 1:
  Input: candies = [2,3,5,1,3], extraCandies = 3
  Output: [true,true,true,false,true]
  Explanation:
  Kid 1 has 2 candies and if he or she receives all extra candies (3) will have 5 candies --- the greatest number of candies among the kids.
  Kid 2 has 3 candies and if he or she receives at least 2 extra candies will have the greatest number of candies among the kids.
  Kid 3 has 5 candies and this is already the greatest number of candies among the kids.
  Kid 4 has 1 candy and even if he or she receives all extra candies will only have 4 candies.
  Kid 5 has 3 candies and if he or she receives at least 2 extra candies will have the greatest number of candies among the kids.

• Example 2:
  Input: candies = [4,2,1,1,2], extraCandies = 1
  Output: [true,false,false,false,false]
  Explanation: There is only 1 extra candy, therefore only kid 1 will have the greatest number of candies among the kids regardless of who takes the extra candy.

• Example 3:
  Input: candies = [12,1,12], extraCandies = 10
  Output: [true,false,true]

由題意及範例可以得知，孩子們所擁有的糖果數量記錄在candies陣列中，另外有額外的糖果由extraCandies變數記錄著；題目在問說每一位孩子的糖果數是否有機會能為最多顆。

var kidsWithCandies = function(candies, extraCandies) {
    const max = Math.max(...candies);
    let result = candies.map((i, idx) => {
      if(i >= max) return true;
      if(i + extraCandies >= max) return true;
      return false;
    });
    return result;
}

Array.map()

• map() 方法會把調用寫入陣列中每個元素逐一傳給你指定的函式，然後傳回一個由函式回傳值所構成的陣列
• 承上，若是函式沒有回傳則是 undefined
• map() 回傳一個新陣列，它不會修改調用它的陣列，如果調用 map() 的陣列是稀疏的，回傳的陣列也會以同樣的方式稀疏

  var a = [1, 2, 3];
  var b = a.map(function(i, idx , model) {
  	return i * i;
  });                          // b 為 [1, 4, 9]
  var c = a.map(i => i);       // 複製 a ； 陣列修改 c 也不會影響到 a