From df2ee95279b356d1be9219d48023340dd61b4454 Mon Sep 17 00:00:00 2001
From: Baoshuo <i@baoshuo.ren>
Date: Sat, 13 Jul 2024 22:18:52 +0800
Subject: [PATCH] =?UTF-8?q?P1496=20=E7=81=AB=E7=83=A7=E8=B5=A4=E5=A3=81?=
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https://www.luogu.com.cn/record/165811402
---
 Luogu/P1496/P1496.cpp        | 54 ++++++++++++++++++++++++++++++++++++
 Luogu/P1496/data/P1496_8.in  |  3 ++
 Luogu/P1496/data/P1496_8.out |  3 ++
 3 files changed, 60 insertions(+)
 create mode 100644 Luogu/P1496/P1496.cpp
 create mode 100644 Luogu/P1496/data/P1496_8.in
 create mode 100644 Luogu/P1496/data/P1496_8.out

diff --git a/Luogu/P1496/P1496.cpp b/Luogu/P1496/P1496.cpp
new file mode 100644
index 00000000..e0a7a76b
--- /dev/null
+++ b/Luogu/P1496/P1496.cpp
@@ -0,0 +1,54 @@
+#include <iostream>
+#include <algorithm>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 2e4 + 5;
+
+int n, ans,
+    l[N], r[N],         // 原位置
+    f[N << 1];          // 染色情况（离散化以后），注意开两倍空间（左右端点）
+std::vector<int> nums;  // 统计出现的数字，离散化用
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n;
+
+    for (int i = 1; i <= n; i++) {
+        cin >> l[i] >> r[i];
+
+        // 统计一下哪些数字出现过
+        nums.push_back(l[i]);
+        nums.push_back(r[i]);
+    }
+
+    // 先排序才能用 std::unique 去重，两个函数都在 <algorithm> 里面定义
+    std::sort(nums.begin(), nums.end());
+    nums.erase(std::unique(nums.begin(), nums.end()), nums.end());  // 去重完移除后面多余的数字
+    // 可以讲一下 std::unique 跑完以后数组的特性：前面不重复且单增，后面是多余的数
+
+    for (int i = 1; i <= n; i++) {
+        // 求出离散化以后的位置
+        int nl = std::lower_bound(nums.begin(), nums.end(), l[i]) - nums.begin(),
+            nr = std::lower_bound(nums.begin(), nums.end(), r[i]) - nums.begin();
+
+        // 这里用差分也可以，不过数据范围比较小，这么写也能过
+        for (int j = nl; j < nr; j++) {
+            f[j] = 1;
+        }
+    }
+
+    for (int i = 0; i < nums.size() - 1; i++) {
+        // 如果被染色就统计一下长度
+        if (f[i]) ans += nums[i + 1] - nums[i];
+    }
+
+    cout << ans << endl;
+
+    return 0;
+}
diff --git a/Luogu/P1496/data/P1496_8.in b/Luogu/P1496/data/P1496_8.in
new file mode 100644
index 00000000..72de9db0
--- /dev/null
+++ b/Luogu/P1496/data/P1496_8.in
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:bac7b9d50ebad0cc319d7718824671385033eb1250de93533de11bd18647c41e
+size 321665
diff --git a/Luogu/P1496/data/P1496_8.out b/Luogu/P1496/data/P1496_8.out
new file mode 100644
index 00000000..25b93046
--- /dev/null
+++ b/Luogu/P1496/data/P1496_8.out
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:9aa210ad9b9c22fdfb8d6a9e232ec885b333874e122aaebdeeaf1d4c2a2f8ecd
+size 12