weixin_53494283: 确实错了，是1,2,3的
Rstudio中安装package问题xiguanqiqi: 我也是，所以还是用了第二种手动的方法
Floyd（弗洛伊德算法） 求最短路径 有向图咸鱼QAQ: 只经过1，2端点的矩阵是不是错了。那是应该是经过1，2，3端点的矩阵
Rstudio中安装package问题白鞋子: 第一种方法不行，还是显示无法打开URL Warning in install.packages : unable to access index for repository https://mirrors.ustc.edu.cn/CRAN/src/contrib: 无法打开URL'https://mirrors.ustc.edu.cn/CRAN/src/contrib/PACKAGES' WARNING: Rtools is required to build R packages but is not currently installed. Please download and install the appropriate version of Rtools before proceeding: https://cran.rstudio.com/bin/windows/Rtools/ Warning in install.packages : unable to access index for repository https://mirrors.ustc.edu.cn/CRAN/src/contrib: 无法打开URL'https://mirrors.ustc.edu.cn/CRAN/src/contrib/PACKAGES' Warning in install.packages : package ‘vcd’ is not available (for R version 4.0.1) Warning in install.packages : unable to access index for repository https://mirrors.ustc.edu.cn/CRAN/bin/windows/contrib/4.0: 无法打开URL'https://mirrors.ustc.edu.cn/CRAN/bin/windows/contrib/4.0/PACKAGES'[code=plain]第一种方法不行，还是显示无法打开URL Warning in install.packages : unable to access index for repository https://mirrors.ustc.edu.cn/CRAN/src/contrib: 无法打开URL'https://mirrors.ustc.edu.cn/CRAN/src/contrib/PACKAGES' WARNING: Rtools is required to build R packages but is not currently installed. Please download and install the appropriate version of Rtools before proceeding: https://cran.rstudio.com/bin/windows/Rtools/ Warning in install.packages : unable to access index for repository https://mirrors.ustc.edu.cn/CRAN/src/contrib: 无法打开URL'https://mirrors.ustc.edu.cn/CRAN/src/contrib/PACKAGES' Warning in install.packages : package ‘vcd’ is not available (for R version 4.0.1) Warning in install.packages : unable to access index for repository https://mirrors.ustc.edu.cn/CRAN/bin/windows/contrib/4.0: 无法打开URL'https://mirrors.ustc.edu.cn/CRAN/bin/windows/contrib/4.0/PACKAGES'[/code]
Floyd（弗洛伊德算法） 求最短路径 有向图css_is_awesome: 厉害厉害