시간 제한메모리 제한제출정답맞힌 사람정답 비율
1 초 128 MB135675563.218%

문제

KDK방송국은 새로운 게임 쇼를 하나 만들었다. 참가자는 선택을 몇 개 하게 되고, 이 선택에 따라서 상품을 얻게 된다.

먼저, 공이 삼각형 모양으로 쌓여져 있고, 각 공에는 정수 값이 하나씩 쓰여 있다. 아래 그림은 한 예이다.

참가자는 공을 고를 수 있고, 고른 공에 쓰여 있는 숫자의 합이 점수가 된다. 공을 고르면, 그 공은 삼각형에서 제거된다. 점수가 높을수록 좋은 상품을 받게 된다. 하지만, 참가자는 그 공의 위에 있는 공을 고른 경우에만 그 공을 고를 수 있다. 또, 참가자는 공을 고를 것인지, 게임을 중단할 것인지 선택할 수 있다. 만약, 공을 하나도 고르지 않은 경우에 점수는 0이 된다.

프로그램 PD 김동규는 참가자들이 얻을 수 있는 점수의 최댓값을 구해보려고 한다. 점수의 최댓값은 몇 점일까?

입력

입력은 여러 개의 테스트 케이스로 이루어져 있다. 각 테스트 케이스의 첫째 줄에는 공이 총 몇 행으로 쌓여져 있는지가 주어진다. 이 값을 N이라고 한다. (1 ≤ N ≤ 1000) 다음 N개의 줄의 i번째 줄에는 총 i개의 정수 Bij가 주어진다. (-105 ≤ Bij ≤ 105, 1 ≤ j ≤ i ≤ N) Bij는 i행 j열에 있는 공에 쓰여 있는 정수이다. (첫 행은 가장 윗 행, 각 행의 첫 번째 공은 가장 왼쪽 공)

입력의 마지막 줄에는 0이 하나 주어진다.

출력

각 테스트 케이스에 대해서, 참가자가 얻을 수 있는 점수의 최댓값을 출력한다.

예제 입력 1

4
3
-5 3
-8 2 -8
3 9 -2 7
2
-2
1 -10
3
1
-5 3
6 -4 1
0

예제 출력 1

7
0
6
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

출처

ICPC > Regionals > Latin America > Latin America Regional Contests 2011 B번

  • 문제를 번역한 사람: baekjoon
  • 문제를 만든 사람: Vinicius Santos