From b6e08801482225a3a7b2d540e7aa4e95cf8fd723 Mon Sep 17 00:00:00 2001
From: Zengtudor <Zengtudor@outlook.com>
Date: Thu, 4 Sep 2025 15:02:33 +0800
Subject: [PATCH] =?UTF-8?q?feat:=20=E6=B7=BB=E5=8A=A0P7992=E5=92=8Clibre10?=
 =?UTF-8?q?115=E4=B8=A4=E4=B8=AA=E7=AE=97=E6=B3=95=E9=97=AE=E9=A2=98?=
 =?UTF-8?q?=E7=9A=84=E8=A7=A3=E5=86=B3=E6=96=B9=E6=A1=88?=
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添加了两个新的算法实现文件：
1. P7992.cpp - 实现了一个基于前缀和的统计问题解决方案
2. libre10115.cpp - 实现了一个使用二叉索引树(Fenwick Tree)的区间查询问题解决方案
---
 src/9/4/P7992.cpp      | 33 +++++++++++++++++++++++++++
 src/9/4/libre10115.cpp | 52 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 85 insertions(+)
 create mode 100644 src/9/4/P7992.cpp
 create mode 100644 src/9/4/libre10115.cpp

diff --git a/src/9/4/P7992.cpp b/src/9/4/P7992.cpp
new file mode 100644
index 0000000..6356c28
--- /dev/null
+++ b/src/9/4/P7992.cpp
@@ -0,0 +1,33 @@
+#include <cstdint>
+#include <iostream>
+#include <istream>
+#include <vector>
+using ll = int64_t;
+
+
+int main(){
+    std::iostream::sync_with_stdio(false);
+    std::cin.tie(nullptr);
+
+    ll n,m;
+    std::cin>>n>>m;
+    std::vector<ll> va(m+1),vb(m+1);
+    for(ll i=1;i<=n;i++){
+        ll a,b;
+        std::cin>>a>>b;
+        va[a]++;
+        vb[b]++;
+    }
+    std::vector<ll> pre(2*m+2);
+    for(ll i=0;i<=m;i++){
+        for(ll j=0;j<=m;j++){
+            pre[i+j]+=va[i]*va[j];
+            pre[i+j+1]-=vb[i]*vb[j];
+        }
+    }
+    ll ans=0;
+    for(ll i=0;i<=2*m;i++){
+        ans+=pre[i];
+        std::cout<<ans<<'\n';
+    }
+}
\ No newline at end of file
diff --git a/src/9/4/libre10115.cpp b/src/9/4/libre10115.cpp
new file mode 100644
index 0000000..e51e1ba
--- /dev/null
+++ b/src/9/4/libre10115.cpp
@@ -0,0 +1,52 @@
+#include <cstdint>
+#include <ios>
+#include <iostream>
+#include <vector>
+using ll = int64_t;
+
+struct BT{
+    const ll size;
+    std::vector<ll> t;
+    static inline ll lb(ll n){
+        return n&(-n);
+    }
+    BT(ll size):size(++size),t(size+1){
+
+    }
+    inline void upd(ll idx,ll add){
+        while(idx<=size){
+            t[idx]+=add;
+            idx+=lb(idx);
+        }
+    }
+    inline ll get(ll idx){
+        ll res=0;
+        while(idx){
+            res+=t[idx];
+            idx-=lb(idx);
+        }
+        return res;
+    }
+};
+
+int main(){
+    std::ios_base::sync_with_stdio(false);
+    std::cin.tie(nullptr);
+
+    ll n,m;
+    std::cin>>n>>m;
+    BT s(n),e(n);
+    for(ll i=1;i<=m;i++){
+        ll k,l,r;
+        std::cin>>k>>l>>r;
+        if(k==1){
+            s.upd(l, 1);
+            e.upd(r, 1);
+        }else{
+            ll nans=
+                s.get(r) - e.get(l-1);
+            
+            std::cout<<nans<<"\n";
+        }
+    }
+}
\ No newline at end of file