From 7df869dba17acfb53d4308bdc973539693e59771 Mon Sep 17 00:00:00 2001
From: ceunnseo <eunseo4068@gmail.com>
Date: Wed, 27 Aug 2025 10:29:07 +0900
Subject: [PATCH] Day03

---
 .../Q2824.js"                                 | 16 ++++
 .../Q1353.js"                                 | 95 +++++++++++++++++++
 2 files changed, 111 insertions(+)
 create mode 100644 "leetcode2/1easy/\354\265\234\354\235\200\354\204\234/Q2824.js"
 create mode 100644 "leetcode2/2medium/\354\265\234\354\235\200\354\204\234/Q1353.js"

diff --git "a/leetcode2/1easy/\354\265\234\354\235\200\354\204\234/Q2824.js" "b/leetcode2/1easy/\354\265\234\354\235\200\354\204\234/Q2824.js"
new file mode 100644
index 00000000..24028d44
--- /dev/null
+++ "b/leetcode2/1easy/\354\265\234\354\235\200\354\204\234/Q2824.js"
@@ -0,0 +1,16 @@
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number}
+ */
+var countPairs = function (nums, target) {
+  let cnt = 0;
+  nums.sort((a, b) => a - b);
+  for (let i = 0; i < nums.length - 1; i++) {
+    for (let j = i + 1; j < nums.length; j++) {
+      if (nums[i] + nums[j] >= target) break;
+      cnt += 1;
+    }
+  }
+  return cnt;
+};
diff --git "a/leetcode2/2medium/\354\265\234\354\235\200\354\204\234/Q1353.js" "b/leetcode2/2medium/\354\265\234\354\235\200\354\204\234/Q1353.js"
new file mode 100644
index 00000000..161e2c5a
--- /dev/null
+++ "b/leetcode2/2medium/\354\265\234\354\235\200\354\204\234/Q1353.js"
@@ -0,0 +1,95 @@
+/**
+ * @param {number[][]} events
+ * @return {number}
+ */
+//많은 이벤트에 참여 -> 종료 날짜가 빠른 이벤트부터 참여한다 (우선순위큐)
+//
+class MyMinHeap {
+  constructor() {
+    this.heap = [];
+  }
+  size() {
+    return this.heap.length;
+  }
+  peek() {
+    if (this.size() > 0) return this.heap[0];
+    else return -1;
+  }
+  enqueue(value) {
+    this.heap.push(value);
+    this.bubbleUp();
+  }
+  bubbleUp() {
+    let cur = this.size() - 1; //자식 노드 인덱스
+    while (cur > 0) {
+      let parent = Math.floor((cur - 1) / 2);
+      if (this.heap[cur] < this.heap[parent]) {
+        [this.heap[cur], this.heap[parent]] = [
+          this.heap[parent],
+          this.heap[cur],
+        ];
+        cur = parent;
+      } else {
+        break;
+      }
+    }
+  }
+  dequeue() {
+    if (this.size() < 1) return;
+    if (this.size() === 1) return this.heap.pop();
+    const mini = this.heap[0];
+    const last = this.heap.pop();
+    this.heap[0] = last;
+    this.bubbleDown(); //정렬
+    return mini;
+  }
+  bubbleDown() {
+    //맨 위 원소를 자기 자리로
+    let cur = 0;
+    while (true) {
+      let left = cur * 2 + 1;
+      let right = cur * 2 + 2;
+      let swap = null;
+      if (left < this.size() && this.heap[left] < this.heap[cur]) {
+        swap = left;
+      }
+      if (right < this.size() && this.heap[right] < this.heap[cur]) {
+        if (swap === null) {
+          swap = right;
+        } else if (swap != null && this.heap[right] < this.heap[left]) {
+          swap = right;
+        }
+      }
+      if (swap === null) break;
+      [this.heap[cur], this.heap[swap]] = [this.heap[swap], this.heap[cur]];
+      cur = swap;
+    }
+  }
+}
+var maxEvents = function (events) {
+  const pq = new MyMinHeap();
+  events.sort((a, b) => a[0] - b[0]); //시작 날짜 빠른 순으로 정렬
+  let startDay = events[0][0]; //가장 빠른 이벤트의 시작 날짜
+  let endDay = 0;
+  for (let i = 0; i < events.length; i++) {
+    endDay = Math.max(endDay, events[i][1]);
+  } //이벤트 마지막 날짜를 구하는 과정이 비효율적임
+  let day = startDay;
+  let cnt = 0;
+  let idx = 0;
+  while (day <= endDay) {
+    while (idx < events.length && events[idx][0] <= day) {
+      pq.enqueue(events[idx][1]);
+      idx += 1;
+    } //오늘(day) 참여할 수 있는 모든 이벤트들을 후보로 지정
+    while (pq.size() > 0 && pq.peek() < day) {
+      pq.dequeue();
+    } //이미 지나버린 이벤트가 있는 경우 -> 삭제 (예시 : day 3, 이벤트 종료일 2일)
+    if (pq.size() > 0) {
+      pq.dequeue();
+      cnt += 1;
+    } //그 중에서 가장 빨리 끝나는 스케줄을 먼저 처리
+    day += 1; //그 다음날
+  }
+  return cnt;
+};