AtCoder Beginner Contest 121 C. Energy Drink Collector【Python】
https://atcoder.jp/contests/abc121/tasks/abc121_c
AtCoder ProblemsのRecommendationで Difficulty: 360、Solve Probability: 48%でした。
N, M = map(int, input().split()) l = [] for i in range(N): l.append(list(map(int, input().split()))) l = sorted(l) cost = 0 count = 0 for i in l: a, b = i left = M-count #残りの必要個数がb以上の場合 if left >= b: cost += a * b count += b #残りの必要個数がb未満の場合 else: cost += a * left count += left if count == 0: break print(cost)