https://leetcode.cn/problems/number-of-students-unable-to-eat-lunch/

Author: masx200

README.md

@@ -71,6 +71,8 @@ https://leetcode.cn/problems/count-number-of-distinct-integers-after-reverse-ope
 
 https://leetcode.cn/problems/possible-bipartition/
 
+https://leetcode.cn/problems/number-of-students-unable-to-eat-lunch/
+
 https://leetcode.cn/problems/construct-binary-search-tree-from-preorder-traversal/
 
 https://leetcode.cn/problems/fruit-into-baskets/

construct-binary-search-tree-from-preorder-traversal/test.ts

@@ -12,7 +12,7 @@ Deno.test("construct-binary-search-tree-from-preorder-traversal", () => {
         [
             [8, 5, 10, 1, 7, null, 12],
             [1, null, 3],
-        ].map(TreeNodeLeetCodeFromJSON)
+        ].map(TreeNodeLeetCodeFromJSON),
     );
     assertEquals(
         [
@@ -24,6 +24,6 @@ Deno.test("construct-binary-search-tree-from-preorder-traversal", () => {
         [
             [8, 5, 10, 1, 7, null, 12],
             [1, null, 3],
-        ]
+        ],
     );
 });

number-of-students-unable-to-eat-lunch/index.ts

@@ -0,0 +1,23 @@
+export default function countStudents(
+    students: number[],
+    sandwiches: number[],
+): number {
+    const cnt = Object.assign([0, 0], countBy(students));
+
+    while (true) {
+        if (students.length === 0) return 0;
+
+        if (cnt[sandwiches[0]] === 0) {
+            return students.length;
+        }
+        if (students[0] === sandwiches[0]) {
+            cnt[students[0]]--;
+            students.shift();
+            sandwiches.shift();
+        } else {
+            students.push(students[0]);
+            students.shift();
+        }
+    }
+}
+import { countBy } from "../deps.ts";