面试题9.1.跳台阶

public class {
  public int jumpFloor(int target){
    if(target == 1)
      return 1;
    if(target == 2)
      return 2;
    int firstStep = 1;
    int secondStep = 2;
    int result = 0;
    
    for(int i = 3; i <= target; i++){
      result = firstStep + secondStep;
      firstStep = secondStep;
      secondStep = result;
    }
    return result;
  }
}