方向遍历顺序说明下一个倒序（从右往左）先处理右侧，栈里存「右侧候选」上一个正序（从左往右）先处理左侧，栈里存「左侧候选」
Charities believe finding people accommodation is only half the battle. The next step is stopping people returning to the streets, and Gareth has come along as much for the mental health boost of seeing familiar faces as for the food parcel.
。关于这个话题，heLLoword翻译官方下载提供了深入分析
Book-style Android with cutting-edge AI, good cameras and great tablet screen for media and multitasking on the go
const stack = []; // 单调递增栈：栈底→栈顶数字递增，保证高位尽可能小
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