문제
Counting Valleys
Gary is an avid hiker. He tracks his hikes meticulously, paying close attention to small details like topography. During his last hike he took exactly steps. For every step he took, he noted if it was an uphill, , or a downhill, step. Gary’s hikes start and end at sea level and each step up or down represents a unit change in altitude.
We define the following terms:
- A mountain is a sequence of consecutive steps above sea level, starting with a step up from sea level and ending with a step down to sea level.
- A valley is a sequence of consecutive steps below sea level, starting with a step down from sea level and ending with a step up to sea level.
Given Gary’s sequence of up and down steps during his last hike, find and print the number of valleys he walked through.
For example, if Gary’s path is , he first enters a valley units deep. Then he climbs out an up onto a mountain units high. Finally, he returns to sea level and ends his hike.
Sample Input : 8 UDDDUDUU
Sample Output : 1
풀이
자바 풀이방식(Java 8)
public static int countingValleys(int steps, String path) {
// Write your code here
int levels = 0;
int result = 0;
for(int i=0; i<steps; i++){
int upNdown = 0;
if(path.charAt(i) == 'U'){
upNdown = 1;
} else {
upNdown = -1;
}
levels = levels + upNdown;
if(upNdown == 1 && levels == 0) result++;
}
return result;
}
설명
- 등산 루트(path)를 한글자씩 읽는다.
- “U” 혹은 “D” 여부에 따라 현재 레벨에서 더하거나 빼준다.
- 만일 현재 level이 0이고, 상승하는 단계였다면 valley이므로 result++ 해준다.
- result를 반환한다.
두둥! 쉬운 문제라서 그런지 참고코드와도 동일했다.
해당 풀이 방법을 기준으로 python으로 작성해보았다.
파이선 풀이 방식
```python 3 def countingValleys(steps, path): # Write your code here result = 0 level = 0 for step in path: upNdown = 0 if step == “U”: upNdown += 1 else: upNdown += -1 level += upNdown
if level == 0 and upNdown == 1 :
result += 1
return result
```
- 문제 URL : Counting Valleys
