题解 | #单调栈#

这个内存使用和运行时间都击败了0.00%的人也太真实了吧 晕死.......

public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param nums int一维数组 
     * @return int二维数组
     */
    public int[][] foundMonotoneStack (int[] nums) {
        // write code here
        int len=nums.length;
        int[][] arr=new int[len][2];
        Stack<Integer> stacks=new Stack<>();
        Stack<Integer> orders=new Stack<>();
        int times=0;
        int index=0;
        while(index!=len){
            if(stacks.empty()){
                arr[index][0]=-1;
                stacks.push(nums[index]);
                orders.push(index);
                index++;
            }else{
                if(nums[index]>stacks.peek()){
                    arr[index][0]=orders.peek();
                    stacks.push(nums[index]);
                    orders.push(index);
                    index++;
                }else{
                    while(nums[index]<=stacks.peek()){
                    
                        stacks.pop();
                        orders.pop();
                        if(stacks.empty()){
                            break;
                        }
    
                    }
                }
               
                // if(!stacks.empty()){
                //     arr[index][0]=orders.peek();
                //     stacks.push(nums[index]);
                //     orders.push(index);
                // }
            }
        }
        stacks.clear();
        orders.clear();
        index=len-1;
        while(index!=-1){
            if(stacks.empty()){
                arr[index][1]=-1;
                stacks.push(nums[index]);
                orders.push(index);
                index--;
            }else{
                if(nums[index]>stacks.peek()){
                    arr[index][1]=orders.peek();
                    stacks.push(nums[index]);
                    orders.push(index);
                    index--;
                }else{
                    while(nums[index]<=stacks.peek()){
                        stacks.pop();
                        orders.pop();
                        if(stacks.empty()){
                            break;
                        }
                    }
                }
                
            }
        }
        return arr;
        
        

    }
}