"Leetcode-Interview algorithm classic-java Implementation" "155-min stack (minimum stack)"

"155-min stack (minimum stack)" "leetcode-Interview algorithm classic-java Implementation" "All topics Directory Index" Original Question

Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.
Push (x) –push element x onto stack.
Pop () –removes the element on top of the stack.
Top () –get the top element.
Getmin () –retrieve the minimum element in the stack.

Main Topic

Design a stack, support push,pop,top, and find the smallest element operation (constant time)

Thinking of solving problems

Use a secondary stack to hold the smallest element in the stack.

Code Implementation

Algorithm implementation class

 Public classMinstack {PrivateFinalStatic intDefault_size = +;Private int[] Stack;Private int[] minindex;Subscript for the smallest element in the stack that holds the first n data    Private intmin = Integer.max_value;//To record the minimum data during the insertion process    Private intindex =-1;//Record the position of the smallest element in the stack    Private intCurrent =-1; Public Minstack() {stack =New int[Default_size]; Minindex =New int[Default_size]; } Public Minstack(intSize) {stack =New int[Size]; Minindex =New int[Size]; } Public void Push(intx) {current++;//move to the location you want to insert        if(Current >= Stack.length) {//Capacity expansion            int[] tmp =New int[Current *2]; System.arraycopy (Stack,0Tmp0, stack.length);            stack = tmp; TMP =New int[Current *2]; System.arraycopy (Minindex,0Tmp0, minindex.length);        Minindex = tmp; } Stack[current] = x;//Insert Data        if(x < min) {//Save the minimum value insertedmin = x; index = current;//Record [0, current] The smallest element subscript is index} minindex[current] = index; } Public void Pop() {current--;if(Current >=0) {min = stack[minindex[current]];//Reset the minimum value in the stackindex = minindex[current];//Reset the index of the minimum value}    } Public int Top() {if(Current <0) {Throw NewRuntimeException ("No more Data"); }returnStack[current]; } Public int Getmin() {if(Current <0) {Throw NewRuntimeException ("No more Data"); }returnStack[minindex[current]]; }}

Evaluation Results

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"Leetcode-Interview algorithm classic-java Implementation" "155-min stack (minimum stack)"