/in/foo.cc:5:17: error: expected type-specifier before numeric constant
 using INT_MAX = 100000000;
                 ^~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:13:31: error: 'INT_MAX' was not declared in this scope
     vector<int> dp(X * 2 + 1, INT_MAX); // 初始化dp数组，大小为2*X+1，初始值为无穷大
                               ^~~~~~~