def BruteForce(pointList):
if len(pointList)<=3:
return pointList
#去重
pointList=list(set(pointList))
#固定A点
A = Tool.findIth(0,len(pointList)-1,pointList,1,lambda x,y:cmp(x[1],y[1]))
pointList.remove(A)
#枚举B,C,P
while 1:
dropList=[]
for b in range(0,len(pointList)-1):
for c in range(b+1,len(pointList)):
for p in range(0,len(pointList)):
if p==b or p==c:
continue
B=pointList[b]
C=pointList[c]
P=pointList[p]
if Tool.isInTriangle(A,B,C,P)==1:
dropList.append(P)
if len(dropList)==0:
break
#去重
dropList=list(set(dropList))
for p in dropList:
pointList.remove(p)
pointList.append(A)
return pointList
def Graham_Scan(pointlist): #构造有序list point = Tool.findIth(0,len(pointlist)-1,pointlist,1,comparePointX)#获取最左边点 uplist = [] downlist=[] otherlist=[] for w in pointlist: if w[0]==point[0] and w[1]==point[1]: continue elif w[0]==point[0] and w[1]>point[1]: uplist.append((w,'+')) elif w[0]==point[0] and w[1]<point[1]: downlist.append((w,'-')) else: otherlist.append((w,float(w[1]-point[1])/(w[0]-point[0]))) #排序 uplist.sort(cmp=lambda x,y:comparePointY(x[0],y[0]),reverse=True)#降序 downlist.sort(cmp=lambda x,y:comparePointY(x[0],y[0]))#升序 otherlist.sort(cmp=lambda x,y:cmp(x[1],y[1]))#按斜率升序 #合并为一个有序list list=[] list.append(point) for w in downlist: list.append(w[0]) for w in otherlist: list.append(w[0]) for w in uplist: list.append(w[0]) #Graham-Scan stack = [] if len(list)<3: return list for w in range(3): stack.append(list.pop(0)) for w in range(len(list)): next = list.pop(0) while isLeftMove(stack[-2],stack[-1],next,point)=='right': stack.pop() if len(stack)<=2: break stack.append(next) return stack
