随机补齐 缺少的城市 (12173)

E2 右拉{=INDEX($1:$1,SMALL(IF(COUNTIF($B2:D2,$B$1:$K$1)=0,COLUMN($B:$K)),RANDBETWEEN(1,10-COLUMNS($B2:D2))))

E2分別複製到 D3 E4 分別右拉

M2{=AND(COUNTIF(B2:K2,B$1:K$1)=1)

另解{=INDEX(1:1,MOD(MIN(IF(COUNTIF($B2:D2,$B1:$K1),"",RANDBETWEEN(COLUMN($B:$K)^0,999)/1%+COLUMN($B:$K))),100))