Go(1.14.4) 解法, 执行用时: 109ms, 内存消耗: 37608K, 提交时间: 2020-08-02 16:55:22

package main

import (
	"math/bits"
	"sort"
)

// github.com/EndlessCheng/codeforces-go
func MaxMin(a []int) int64 {
	type pair struct{ x, y int }
	n := len(a)
	st := make([][17]pair, n)
	for i, v := range a {
		st[i][0] = pair{v, v}
	}
	for j := 1; 1<<j <= n; j++ {
		for i := 0; i+1<<j <= n; i++ {
			st[i][j].x = min(st[i][j-1].x, st[i+1<<(j-1)][j-1].x)
			st[i][j].y = max(st[i][j-1].y, st[i+1<<(j-1)][j-1].y)
		}
	}
	s := 0
	for r := 1; r <= n; r++ {
		s += sort.Search(r, func(l int) bool {
			k := bits.Len(uint(r-l)) - 1
			x, y := st[l][k], st[r-1<<k][k]
			return max(x.y, y.y) < min(x.x, y.x)<<1
		})
	}
	return int64(s)
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}
func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

Java(javac 1.8) 解法, 执行用时: 6207ms, 内存消耗: 29952K, 提交时间: 2021-04-02 23:46:39

import java.util.*;


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 array int整型一维数组 array
     * @return long长整型
     */
    public long MaxMin (int[] nums) {
        // write code here
        long res = 0;
        long n = nums.length;
        for (int j = 0; j < n; j++) {
            long mx = nums[j], mn = nums[j];
            for (int i = j - 1; i >= 0; i--) {
                mx = Math.max(mx, nums[i]);
                mn = Math.min(mn, nums[i]);
                if (mx >= 2 * mn) res++;
            }
        }
        return res;
    }
}

C++11(clang++ 3.9) 解法, 执行用时: 39ms, 内存消耗: 5024K, 提交时间: 2020-08-09 18:48:27

class Solution
{
	public:
		long long MaxMin(int *a,int n)
		{
			long long ans=0;
			for(int i=0;i<n;i++)
			{
				int mi=1e9+1,mx=0;
				for(int j=i;j<n;j++)
				{
					mi=min(mi,a[j]);
					mx=max(mx,a[j]);
					if(mx>=2*mi)
					{
						ans+=n-j;
						break;
					}
				}
			}
			return ans;
		}
};