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POhow to implement 3 stack in a single array efficiently?
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  1. POhow to implement 3 stack in a single array efficiently?
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    copied!<p>it is a python code..whether implementing using linked list .... is efficient in this way...........</p> <pre><code>data = [] # data storage for stacks represented as linked lists stack = [-1, -1, -1] # pointers to each of three stacks (-1 is the "null" pointer) free = -1 # pointer to list of free stack nodes to be reused def allocate(value): ''' allocate a new node and return a pointer to it ''' global free global data if free == -1: # free list is empty, need to expand data list data += [value,-1] return len(data)-2 else: # pop a node off the free list and reuse it temp = free free = data[temp+1] data[temp] = value data[temp+1] = -1 return temp def release(ptr): ''' put node on the free list ''' global free temp = free free = ptr data[free+1] = temp def push(n, value): ''' push value onto stack n ''' global free global data temp = stack[n] stack[n] = allocate(value) data[stack[n]+1] = temp def pop(n): ''' pop a value off of stack n ''' value = data[stack[n]] temp = stack[n] stack[n] = data[stack[n]+1] release(temp) return value def list(ptr): ''' list contents of a stack ''' while ptr != -1: print data[ptr], ptr = data[ptr+1] print def list_all(): ''' list contents of all the stacks and the free list ''' print stack,free,data for i in range(3): print i,":", list(stack[i]) print "free:", list(free) push(0,"hello") push(1,"foo") push(0,"goodbye") push(1,"bar") list_all() pop(0) pop(0) push(2,"abc") list_all() pop(1) pop(2) pop(1) list_all() </code></pre> <p>r there is any way to do this efficiently other than this??implement in this way in c /c++ would be eficient???</p>
 

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