update

src/P1087/P1087.cpp

@@ -0,0 +1,39 @@
+#include <iostream>
+#include <string>
+
+using ll = long long;
+
+auto &is = std::cin;
+auto &os = std::cout;
+
+// const ll max_n = 10+2;
+
+ll _;
+std::string s;
+
+void dfs(const ll start, const ll end)noexcept{
+    if(start < end-1){
+        const ll mid {(start+end)/2};
+        dfs(start,mid);
+        dfs(mid,end);
+    }
+    bool is_not_B = false,is_not_I = false;
+    for(ll i{start};i!=end;i++){
+        if(s[i]!='0')is_not_B=true;
+        if(s[i]!='1')is_not_I=true;
+    }
+    if(!is_not_B){
+        os<<'B';
+    }else if(!is_not_I){
+        os<<'I';
+    }else{
+        os<<'F';
+    }
+}
+
+int main(){
+    is>>_;
+    is>>s;
+
+    dfs(0,s.size());
+}