(hdu step 7.1.4)Surround the Trees(求凸包的周长——计算将所有点都包围起来的最小凸多边形的周长)
题意:SurroundtheTreesTimeLimit:2000/1000MS(Java/Others)MemoryLimit:65536/32768K(Java/Others)TotalSubmission(s):209AcceptedSubmission(s):104 ProblemDescriptionTherearealotoftreesinanarea.Apeasantwantstob