题面:https://www.cnblogs.com/Juve/articles/11602450.html u: 用差分优化修改 二维差分:给(x1,y1),(x2,y2)加上s: $d[x1][y1]+=s,d[x1][y2+1]-=s,d[x2+1][y1]-=s,d[x2+1][y2+1]+=s$ 定义2个差分数组d1,d2,分别记录竖列和斜边的差分 $d1[r][c]+=s,d1[r+l-1][c]-=s,d2[r][c+1]-=s,d2[r+l-1][c+l-1]+=s$ 统计是求2…