From bcf4b5e34e49a2db76cd6bab47b1779e3b7a3e2e Mon Sep 17 00:00:00 2001
From: Baoshuo <i@baoshuo.ren>
Date: Sat, 13 Jul 2024 22:57:59 +0800
Subject: [PATCH] =?UTF-8?q?P1147=20=E8=BF=9E=E7=BB=AD=E8=87=AA=E7=84=B6?=
 =?UTF-8?q?=E6=95=B0=E5=92=8C?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

https://www.luogu.com.cn/record/165820608
---
 Luogu/P1147/P1147.cpp | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/Luogu/P1147/P1147.cpp b/Luogu/P1147/P1147.cpp
index d5740004..aae8017f 100644
--- a/Luogu/P1147/P1147.cpp
+++ b/Luogu/P1147/P1147.cpp
@@ -2,22 +2,27 @@
 
 using std::cin;
 using std::cout;
-#define endl '\n'
+const char endl = '\n';
 
-int m, sum, j;
+int m;
 
 int main() {
     std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
     cin >> m;
-    for (int i = 1; i <= m / 2; i++) {
-        sum = 0;
-        for (j = i; j < m; j++) {
-            sum += j;
-            if (sum >= m) break;
-        }
-        if (sum == m) {
+
+    // 为什么到 m/2 结束？因为 m/2 之后的数不可能连着取两个数之和等于 m。
+    for (int i = 1, j = 2, sum = 3 /* 初始 1 + 2 = 3 */; i <= (m >> 1);) {
+        if (sum == m) {  // 够了，输出答案，并且把左面的数从窗口中删去
             cout << i << ' ' << j << endl;
+            sum -= i++;        // 压行：sum -= i; i++;
+        } else if (sum < m) {  // 不够，需要往后再取一个数
+            sum += ++j;        // 压行：j++; sum += j;  # 注意：这里是先加 j 再加 sum，顺序要写对
+        } else {               // sum > m    # 多了，把左面的数从窗口中删去
+            sum -= i++;        // 压行：sum -= i; i++;
         }
     }
+
     return 0;
 }