计数问题(数位DP) https://blog.youkuaiyun.com/qiaoxinwei/article/details/110420115 #include <iostream> #include <vector> using namespace std; //获取v中第l位到r位的数 int get(vector<int> v, int l, int r){ int res = 0; for(int i = l; i >= r; i--) res = res * 10 + v[i]; return res; } //求10的x次幂 int pow10(int x){