860 - Lemonade Change

 JAVA

• class Solution {
      public boolean lemonadeChange(int[] bills) {
          int five = 0, ten = 0;
          for (int v : bills) {
              switch (v) {
                  case 5 -> ++five;
                  case 10 -> {
                      ++ten;
                      --five;
                  }
                  case 20 -> {
                      if (ten > 0) {
                          --ten;
                          --five;
                      } else {
                          five -= 3;
                      }
                  }
              }
              if (five < 0) {
                  return false;
              }
          }
          return true;
      }
  }

C++

• class Solution {
  public:
      bool lemonadeChange(vector<int>& bills) {
          int five = 0, ten = 10;
          for (int v : bills) {
              if (v == 5) {
                  ++five;
              } else if (v == 10) {
                  ++ten;
                  --five;
              } else {
                  if (ten) {
                      --ten;
                      --five;
                  } else {
                      five -= 3;
                  }
              }
              if (five < 0) {
                  return false;
              }
          }
          return true;
      }
  };