Java (OpenJDK 8), 93(削除) 93 (削除ここまで) 81 bytes
s->{booleanint w=falsew=0,p=w,l;for(char c:s){l="aeiouy"w|=p&(p=l="aeiouy".indexOf(c)<0;w=p&&l||w;p=l;}return!(w|p>>31);;return w+p>=0;}
Java (OpenJDK 8), 93 bytes
s->{boolean w=false,p=w,l;for(char c:s){l="aeiouy".indexOf(c)<0;w=p&&l||w;p=l;}return!(w|p);}
Java (OpenJDK 8), (削除) 93 (削除ここまで) 81 bytes
s->{int w=0,p=w,l;for(char c:s)w|=p&(p=l="aeiouy".indexOf(c)>>31);return w+p>=0;}
Java (OpenJDK 8), 93 bytes
s->{boolean w=false,p=w,l;for(char c:s){l="aeiouy".indexOf(c)<0;w=p&&l||w;p=l;}return!(w|p);}