946. 验证栈序列 中等

  1. class Solution {
  2.     public boolean validateStackSequences(int[] pushed, int[] popped) {
  3.         LinkedList<Integer> stack = new LinkedList<>();
  4.         int n = pushed.length;
  5.         int index = 0;
  6.         for (int i=0; i<n; i++) {
  7.             int cur = popped[i];
  8.             for ( ; index<=n; index++) {
  9.                 if (!stack.isEmpty() && stack.getLast() == cur) {
  10.                     stack.pollLast();
  11.                     break;
  12.                 }
  13.                 if (index < n) {
  14.                     stack.addLast(pushed[index]);
  15.                 }                  
  16.             }
  17.         }
  18.         return stack.isEmpty();
  19.     }
  20. }