vector v {1,2,3,4};reverse(v.begin(), v.end());// v 变成 {4,3,2,1}int a[] {1,2,3,4};int n 4;reverse(a, a n);// a 变成 {4,3,2,1}string s “1234”;reverse(s.begin(), s.end());// s 变成 “4321”