分支限界法的0-1背包问题Python实现

<pre name="code" class="python">重量为[3,5,2,1]值为[9,10,7,4]

背包的总重为7，主要运用的queue的特性

#coding : utf-8import numpy as npimport Queueimport mathw = [3,5,2,1]#weightv = [9,10,7,4]#valuedef test(capacity):    vec_len = 2**(len(v)+1) - 1#tree `s size    vec_v = np.zeros(vec_len)    vec_w = np.zeros(vec_len)    vec_w[0]=capacity    que = Queue.Queue();    que.put(0)    best = 0    while(not que.empty()):        current = que.get()        level = int(math.log(current+1,2))        if(vec_v[current] > vec_v[best]):            best = current        left = 2*current+1#left child   index        right = 2*current+2#right child index        if(left < vec_len and vec_w[current]-w[level] > 0 and vec_v[current]+v[level] > vec_v[best] ):            vec_v[left] = int(vec_v[current]+v[level])            vec_w[left] = vec_w[current]-w[level]            que.put(left)        if(right < vec_len and sum(v[level+1:-1])+vec_v[current] > vec_v[best]):            vec_v[right] = vec_v[current]            vec_w[right] = vec_w[current]            que.put(right)    print vec_w[best],vec_v[best]if  __name__ == '__main__':    test(7)