google code jam exercise——MilkShakes(3)

还是MilkShakes的问题。今天看了一下Contest Analysis，按照提示总算得到了较好的结果。

在Contest Analysis中，给出了算法的描述，如下：

1. 初始化flavor choice全为0，检查customer的满意情况；

2. 对于不满意的customer，如果他只喜欢unmalted的，但是所有的已经malted，那么该customer不可能被满足，给出IMPOSSIBLE；

3. 对于不满意的customer，如果他只有一种喜欢的malted，那么将对应的malted，回到步骤2；

4. 如果没有不满意的customer，那么就是得到了解。

在用Python实现的时候，做了一些改进，步骤如下：

1. 初始化flavor choice
遍历所有customer，如果他只喜欢一种flavor，那么要满足他就必须把对应的flavor设为对应的状态。如果在他之前已经被设定为不同的状态，那么他就不可能被满足，给出IMPOSSIBLE，否则，将没有被设定的flavor设定为0，继续下面步骤；

2. 检查所有customer是否满意，如果满意，给出flavor的序列，否则进入循环2-3；

3. 更新flavor choice

遍历不满意的customer，统计他喜欢的malted的个数，如果为0，即该customer只喜欢unmalted，那么他不可能被满足，给出IMPOSSIBLE，如果为1，那么将对应的flavor设为1，即完成flavor choice的更新

代码如下：

#!/usr/bin/python
#encoding:UTF-8
#Filename:MilkShakes_Good.py

import sys

def preChoice(customers,flavorNum):
    flag = 1
    flavorSure = []
    flavorChoice = []
    for i in range(flavorNum):
        flavorChoice.append(-1)
        flavorSure.append(0)

    for i,customer in enumerate(customers):
        if customer[0]==1:
            if flavorChoice[customer[1]-1]==-1:
                flavorChoice[customer[1]-1] = customer[2]
            elif flavorChoice[customer[1]-1]!=customer[2]:
                flag = 0
                break
            flavorSure[customer[1]-1] = 1

    return [flag,flavorSure,flavorChoice]

def checkSatisfy(customerNum,customers,flavorChoice):
#    for k,sat in enumerate(customerSatisfy):
#        if sat==0:
 customerSatisfy = []
    for i in range(customerNum):
        customerSatisfy.append(0)
    for k in range(customerNum):
        customer = customers[k]
        for i in range(customer[0]):
            j = 2 * i + 1
            if flavorChoice[customer[j]-1]==customer[j+1]:
                customerSatisfy[k] = 1
                break
    return customerSatisfy

def checkAllSatisfy(customerSatisfy):
    flag = 1
    for v in customerSatisfy:
        if v==0:
            flag = 0
            break
    return flag


def updateChoice(customers,flavorSure,flavorChoice,customerSatisfy):
    flag = 1
    twoflag = 1 
    for k,v in enumerate(customerSatisfy):
        if v==0:
            customer = customers[k]
            index = []
            for i in range(customer[0]):
                j = 2 * i + 1
                if customer[j+1]==1:
                    index.append(j)
            if len(index)==0:
                flag = 0
                break
            elif len(index)==1:
                flavorSure[customer[index[0]]-1] = 1
                flavorChoice[customer[index[0]]-1] = 1
                twoflag = 0
                break

    if twoflag==1:
        print "two more malted in unsatisfied customer\n"
    return [flag,flavorSure,flavorChoice]



inname = "input.txt"
outname = "output.txt"
if len(sys.argv)>1:
    inname = sys.argv[1]
    outname = inname.rstrip(".in")
    outname = outname + ".out"
fin = open(inname,"r")
fout = open(outname,"w")

line = fin.readline()

testCaseNum = int(line)

caseNum = 0

for caseNum in range(testCaseNum):
    line = fin.readline()
    flavorNum = int(line)
    line = fin.readline()
    customerNum = int(line)
    customers = []
#    for line in lines:
#    print "Case #%d:" %(caseNum+1)
#    print flavorNum
#    print customerNum
 for i in range(customerNum):
        line = fin.readline()
        line = line.rstrip("\n")
        customer = [int(val) for val in line.split()]
#        print customer
 customers.append(customer)

#    print "\n"

    answer = "Case #%d:" %(caseNum+1)

    tpre = preChoice(customers,flavorNum)

#    print "pre choice:"
#    print tpre

    flag = tpre[0]
    if flag == 0:
        answer = answer + " IMPOSSIBLE"
    else:
        flavorSure = tpre[1]
        flavorChoice = tpre[2]
        for i in range(flavorNum):
            if flavorChoice[i]==-1:
                flavorChoice[i] = 0
        customerSatisfy = checkSatisfy(customerNum,customers,flavorChoice)
#        print customerSatisfy
 　　　　allSatisfy = checkAllSatisfy(customerSatisfy) 
#        print allSatisfy

        while(allSatisfy==0):
            tpre = updateChoice(customers,flavorSure,flavorChoice,customerSatisfy)
#            print "update:"
#            print tpre
 　　　　　　flag = tpre[0]
            if flag==0:
                break
            else:
                flavorSure = tpre[1]
                flavorChoice = tpre[2]
                customerSatisfy = checkSatisfy(customerNum,customers,flavorChoice)
                allSatisfy = checkAllSatisfy(customerSatisfy) 
        
        if flag==0:
            answer = answer + " IMPOSSIBLE"
        else:
            for val in flavorChoice:
                answer = answer + " " + str(val)

    answer = answer + "\n"
        
    fout.write(answer)

fin.close()
fout.close()

这次，small／large case都测试通过。