add stl.

stl/map.cpp

@@ -0,0 +1,17 @@
+#include <algorithm>
+#include <iostream>
+#include <map>
+#include <string>
+
+using namespace std;
+
+int main() {
+    map<int, string> itos;
+    itos.insert({1, "abc"});
+    itos.insert({2, "def"});
+    itos.insert({3, "ghi"});
+
+    auto it = itos.find(2);
+    it = find_if(itos.begin(), itos.end(), [](pair<int, string> p) { return p.second.find("g") != string::npos; });
+    cout << it->first << ": " << it->second << endl;
+}