From 8530e20eb0aa27f2fe29bf71c600f3d269e39dfc Mon Sep 17 00:00:00 2001
From: Baoshuo <i@baoshuo.ren>
Date: Fri, 18 Nov 2022 13:56:14 +0800
Subject: [PATCH] #3631. Swap

http://www.nfls.com.cn:20035/submission/591497
---
 NFLSOJ/0/3631/3631.cpp | 46 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 NFLSOJ/0/3631/3631.cpp

diff --git a/NFLSOJ/0/3631/3631.cpp b/NFLSOJ/0/3631/3631.cpp
new file mode 100644
index 00000000..8980c922
--- /dev/null
+++ b/NFLSOJ/0/3631/3631.cpp
@@ -0,0 +1,46 @@
+// #include <iostream>
+#include <algorithm>
+#include <fstream>
+#include <utility>
+#include <vector>
+
+// using std::cin;
+// using std::cout;
+std::ifstream cin("swap.in");
+std::ofstream cout("swap.out");
+const char endl = '\n';
+
+const int N = 1e5 + 5;
+
+int n, a[N], p[N];
+std::vector<std::pair<int, int>> ans;
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n;
+
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i];
+
+        p[a[i]] = i;
+    }
+
+    for (int i = 1; i <= n; i++) {
+        if (a[i] != i) {
+            int x = i, y = p[i];
+            ans.emplace_back(p[x], p[y]);
+            std::swap(a[x], a[y]);
+            p[a[x]] = x, p[a[y]] = y;
+        }
+    }
+
+    cout << ans.size() << endl;
+
+    for (auto e : ans) {
+        cout << e.first << ' ' << e.second << endl;
+    }
+
+    return 0;
+}