剑指offer_递归与循环---跳台阶

/**
 * 
 */
package 递归和循环;
/**
 * <p>
 * Title:JumpFloor
 * </p>
 * <p>
 * Description:
 * </p>
 * 
 * @author 田茂林
 * @data 2017年8月23日 上午11:31:34
 */
public class JumpFloor {
    public int IntJumpFloor(int target) {
        if(target==1){
            return 1;
        }
        if(target==2){
            return 2;
        }
        int num =0;
        if(target>2){
            num = IntJumpFloor(target-1)+IntJumpFloor(target-2);
        }
        return num;
    }
    //==============================================迭代版本
    public int IntJumpFloorSuper(int target) {
        if(target==1){
            return 1;
        }
        if(target==2){
            return 2;
        }
        int before =2;
        int beforeagain =1;
        int end =0;
        for (int i = 3; i <=target; i++) {
            end  = before+beforeagain;
            beforeagain = before;
            before = end;
        }
        return end;
    }
}