一道奥数题,哪位神人帮忙解答一下?

分类讨论呗 1。x<a y=a+b+c+d-4x>b+c+d-3a 2.a<=x<b y=b-a+c+d-2x>c+d-b-a 3.b<=x<c y=c+d-a-b 4.c<=x<d y=2x+d-c-b-a>=d+c-b-a 5.d<=x y=4x-a-b-c-d>=3d-a-b-c 而c+d-a-b<3d-a-b-c 所以最小值为c+d-a-b,此时b<=x<=c