设有n种不同面值的硬币，第i种硬币的币值是vk(其中v1=1)，重量是wi，i=1,
2,...,n且现在购买总价值为y的某些商品，需要用这些硬币付款，如果每种钱币使用的个数不限，问如何选择付款的方法使得付出钱币的总重量最轻？设计一个求解该问题的算法，给出算法的伪码描述并分析算法的时间复杂度.假设问题的输入实例是：
v1=1，v2=4，v3=6，v4=8
w1=1，w2=2，w3=4，w4=6
y=12
给出算法在该实例上计算的备忘录表和标记函数表,并说明付钱的方法。(There is an investigation team to the field investigation, there are N sites on the inspection route that can be used as camping sites. The known distance from the campsite to the starting point is x1, X2,..., xn, and X1 < x2 <... < xn. They can only advance 30 kilometers a day, and the distance between any two adjacent campsites is no more than 30 kilometers. They want to find an action plan to minimize the total number of camping days. Design an algorithm to solve this problem. The main steps of the algorithm are given, the correctness of the algorithm is proved, and the time complexity of the algorithm is estimated.)