样例 {10,15,20} 的输出

#include <iostream>
#include <vector>
using namespace std;

int compute(vector<int>& cost) {
  int n = cost.size();
  vector<int> dp(n + 1, 0);
  dp[1] = cost[0];
  for (int i = 2; i <= n; i++) {
    dp[i] = min(dp[i - 1], dp[i - 2]) + cost[i - 1];
  }
  return min(dp[n], dp[n - 1]);
}

int main() {
  int n;
  cin >> n;
  vector<int> cost(n);
  for (int i = 0; i < n; i++) {
    cin >> cost[i];
  }
  cout << compute(cost) << endl;
  return 0;
}