DP or Greedy - they are all in O(n)
In editorial, a beautiful Greedy solution is given: "To reach the last cloud in a minimum number of steps, always try make a jump from i to i + 2. If that is not possible, jump to i + 1. ". And here is my DP solution:
#include <vector> #include <iostream> using namespace std; int main(){ int n; cin >> n; vector<int> c(n); for(int c_i = 0;c_i < n;c_i++){ cin >> c[c_i]; } vector<int> dp(n, INT_MAX); dp[0] = 0; for(int i = 1; i < n; i++) { if(i > 0 && !c[i-1]) { dp[i] = min(dp[i] ,dp[i - 1] + 1); } if(i>1 && !c[i - 2]) { dp[i] = min(dp[i], dp[i - 2] + 1); } } cout << dp.back() << endl; return 0; }