add: 柠檬水找零

README.md

@@ -338,6 +338,11 @@ LeetCode 与 LintCode 解题记录。此为个人练习仓库，代码中对重
 
   - LintCode 1613. 最高频率的IP <https://www.lintcode.com/problem/highest-frequency-ip/description>
 
+- [柠檬水找零](src/array/lemonade-change.js)
+
+  - LeetCode 860. 柠檬水找零 <https://leetcode-cn.com/problems/lemonade-change/>
+  - LintCode 1509. 柠檬水找零 <https://www.lintcode.com/problem/lemonade-change/description>
+
 ## 栈
 
 - [最大矩阵](src/stack/maximal-rectangle.js)

src/array/lemonade-change.js

@@ -0,0 +1,31 @@
+/**
+ * @param {number[]} bills
+ * @return {boolean}
+ */
+export const lemonadeChange = function (bills) {
+  const map = new Map()
+
+  while (bills.length) {
+    const money = bills.shift()
+
+    if (money === 5) {
+      map.set(5, (map.get(5) || 0) + 1)
+    } else {
+      let change = money - 5
+      while (change !== 0 && change - 10 > 0 && map.get(10) > 0) {
+        map.set(10, map.get(10) - 1)
+        change -= 10
+      }
+
+      while (change !== 0 && map.get(5) > 0) {
+        map.set(5, map.get(5) - 1)
+        change -= 5
+      }
+
+      if (change !== 0) return false
+      map.set(money, (map.get(money) || 0) + 1)
+    }
+  }
+
+  return true
+}

test/array/lemonade-change.test.js

@@ -0,0 +1,9 @@
+import { lemonadeChange } from '../../src/array/lemonade-change'
+
+test('柠檬水找零', () => {
+  expect(lemonadeChange([5, 5, 5, 5, 10, 5, 10, 10, 10, 20])).toBe(true)
+  expect(lemonadeChange([5, 5, 5, 10, 20])).toBe(true)
+  expect(lemonadeChange([5, 5, 10])).toBe(true)
+  expect(lemonadeChange([10, 10])).toBe(false)
+  expect(lemonadeChange([5, 5, 10, 10, 20])).toBe(false)
+})