feat: 添加两个新的算法题目解决方案文件

添加 valid-triangle-number.cpp 和 P11231.cpp 两个文件，分别包含三角形数验证问题和P11231问题的解决方案

src/9/26/P11231.cpp

@@ -0,0 +1,33 @@
+#include <algorithm>
+#include <cstdint>
+#include <cstdio>
+#include <iostream>
+#include <istream>
+#include <map>
+
+using ll = int64_t;
+ll n;
+std::map<ll, ll> r;
+
+int main(){
+    std::iostream::sync_with_stdio(false);
+    std::cin.tie(nullptr);
+
+    std::cin>>n;
+    for(ll i=1;i<=n;i++){
+        ll tmp;
+        std::cin>>tmp;
+        r[tmp]++;
+    }
+    auto idx = r.begin();
+    ll lessn=idx->second;
+    idx++;
+    ll ans=0;
+    for(;idx!=r.end();idx++){
+        ll candel = std::min(idx->second,lessn);
+        lessn-=candel;
+        lessn+=idx->second;
+        ans+=candel;
+    }
+    std::cout<<n-ans<<"\n";
+}

src/9/26/valid-triangle-number.cpp

@@ -0,0 +1,13 @@
+#include <cstdint>
+#include <cstdlib>
+#include <vector>
+using namespace std;
+
+class Solution {
+public:
+    using ll = int64_t;
+    int triangleNumber(vector<int>& nums) {
+        
+    }
+};
+int main(){}