Ubuntu18.04 apt和手动安装JDK原网址内容openjdk，apt安装jdk，apt安装检查版本手动设置默认JAVA版本手动安装JDK原网址https://linuxconfig.org/how-to-install-java-on-ubuntu-18-04-bionic-beaver-linux内容openjdk，apt安装sudo apt install openjdk-...

#include "iostream"#include "algorithm"#include "string"using namespace std;int main(){int a,b,c;cin >> a >> b;c = a + b;if(c<0)cout << '-';...