Determine if the stacking order is correct (stack push, pop-up sequence)

Enter a sequence of two integers. One of the sequences represents the push order of the stack, judging whether another sequence is likely to be the corresponding pop order. For the sake of simplicity, we assume that any two integers of the push sequence are not equal.

For example, the input push sequence is 1, 2, 3, 4, 5, then 4, 5, 3, 2, 1 may be a pop series. Because you can have the following push and pop sequence: Push 1,push 2,push 3,push 4,pop,push 5,pop,pop,pop,pop, so the resulting pop sequence is 4, 5, 3, 2, 1. But sequences 4, 3, 5, 1, 2 are not likely to be the sequence of pop sequences of the push sequence 1, 2, 3, 4, 5.

Directly on the code, there are two ways.

 Packagetest;ImportJava.util.Stack; Public classStackpopseq {/*** According to the number arrangement characteristics * if A[I+1] > A[i], then a[i+1] is greater than the previous number * that is, if the number of small to large out, must be in the out, then larger than their number, it is impossible to come out earlier than them *@paramA *@return     */    Private Static BooleanIspopseqbyno (int[] a) {BooleanFlag =true; intmax = A[0];  for(inti=1;i<a.length;i++){                if(a[i-1]<a[i]&&a[i]<max) {Flag=false;  Break; } Max= Math.max (Math.max (a[i-1],a[i]), Max); }            returnFlag;}/*** Through the simulation stack in and out to judge, * first for the loop to the ARR1 elements in the stack, and on each traversal, retrieve the arr2 can be pop elements. * If the loop ends, and there are elements in the stack, the arr2 sequence is not a pop sequence. * @paramA1 *@paramA2 *@return */    Private Static BooleanIspopseqbysimulate (int[] A1,int[] A2) {        //TODO auto-generated Method StubStack S=NewStack ();  for(inti=0,j=0;i<a1.length;i++) {s.push (a1[i]);  while(!s.empty () &&a2[j]== (int) S.peek ()) {s.pop (); J++; }                    }                returnS.size () ==0; }         Public Static voidMain (String[]args) {int[]a1={1,2,3,4,5,6,7}; int[]a2={1,2,3,7,6,5,4}; int[]a3={1,2,3,7,5,6,4};        System.out.println (Ispopseqbysimulate (A1,A2));                System.out.println (Ispopseqbysimulate (A1,A3));        System.out.println (Ispopseqbyno (A2));            System.out.println (Ispopseqbyno (A3)); }    }

Determine if the stacking order is correct (stack push, pop-up sequence)