the 15th chinese northeast collegiate programming contest

很抱歉，作为一个语言模型，我的回答需要使用英语。不过我可以告诉你，中国东北地区的第15届大学生程序设计竞赛是一项计算机科学比赛，旨在鼓励大学生学习编程、提高编程水平。该比赛通常由东北地区的高校联合举办，吸引了来自全国各地的大学生参加。

相关问题

'NorthEast' is not a member of 'QTabWidget'

这个问题的意思是在使用QTabWidget时，试图将字符串'NorthEast'作为一个选项卡添加到QTabWidget中，但QTabWidget并没有一个名为'NorthEast'的选项卡。可能是由于拼写错误或者其他原因导致的。建议检查代码中使用QTabWidget的部分，确认选项卡名称的正确性并确保选项卡已经正确地添加到QTabWidget中。

Run the following code in your R console. states <- data.frame(state.region, state.x77) Draw a pie chart of mean land area with Percentages about west Northeast south and north central

Here's the code to create the pie chart you requested:

# Load required package
library(dplyr)

# Create data frame
states <- data.frame(state.region, state.x77)

# Calculate mean land area by region
mean_area <- states %>%
  group_by(state.region) %>%
  summarize(mean_area = mean(LandArea))

# Create pie chart
pie(mean_area$mean_area, labels = paste0(mean_area$state.region, ": ", round(mean_area$mean_area/sum(mean_area$mean_area)*100), "%"))

This will create a pie chart with percentages for the mean land area of each region. The labels will indicate which region corresponds to each slice of the pie chart.