155. Min Stack

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不是min就直接push一個min刀minStack

 

 1 class MinStack { 2  3     /** initialize your data structure here. */ 4     Stack<Integer> stack, min; 5     public MinStack() { 6         stack = new Stack<>(); 7         min = new Stack<>();     8     } 9     10     public void push(int x) {11         stack.push(x);12         if(min.isEmpty() || x <= min.peek()){13             min.push(x);14         }else{15             min.push(min.peek());16         }17         18     }19     20     public void pop() {21         stack.pop();22         min.pop();23         24     }25     26     public int top() {27         return stack.peek();28         29     }30     31     public int getMin() {32         return min.peek();33     }34 }

 

155. Min Stack