题目：

题解：

func maxEnvelopes(envelopes [][]int) int {n := len(envelopes)if n == 0 {return 0}sort.Slice(envelopes, func(i, j int) bool {a, b := envelopes[i], envelopes[j]return a[0] < b[0] || a[0] == b[0] && a[1] > b[1]})f := make([]int, n)for i := range f {f[i] = 1}for i := 1; i < n; i++ {for j := 0; j < i; j++ {if envelopes[j][1] < envelopes[i][1] {f[i] = max(f[i], f[j]+1)}}}return max(f...)
}func max(a ...int) int {res := a[0]for _, v := range a[1:] {if v > res {res = v}}return res
}