01背包和背包完全

RT。职务地址http://zju.acmclub.com/index.php?app=problem_title&id=1&problem_id=2123

ps：（1）01背包和全然背包的差别在于计算方向，01背包的计算顺序是从上往下，从右往左；全然背包则是从上往下，从左往右

（2）背包是否装满的差别在于初始化第0行，若不一定装满则所有初始化为0，

若要求必须装满则dp[0]=0,dp[1~C]=（求最小值时初始化为INF，求最大值时初始化为-INF）

（3）终于返回的dp[C]即为结果。

python代码：

#coding=utf-8
INF = 1000000
def Matrix(rows,cols):
    #matrix = [[0 for col in range(cols)] for row in range(rows)]
    matrix = [0 for col in range(cols)]
    return matrix

t = input()
while t:
    [x,y]=raw_input().split()
    C=int(y)-int(x)
    lines=input()
    n = lines
    weight = []
    price = []
    while lines:
        [a,b]=raw_input().split()
        weight.append(int(b))
        price.append(int(a))
        lines -= 1
        if lines==0:break
    mat = Matrix(n+1,C+1)
    #init row-0 in matrix
    mat[0]=0
    for j in range(1,C+1):mat[j]=INF
    #compute the matrix
    for i in range(1,n+1):
        for j in range(weight[i-1],C+1):
            mat[j]=min(mat[j],mat[j-weight[i-1]]+price[i-1])
    if mat[C]==INF:print "This is impossible."
    else: print "The minimum amount of money in the piggy-bank is %d." % mat[C]
    t -= 1
    if t==0:break

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