CF873B

CF873B Balanced Substring (前缀和) 蛮有意思的一道题,不过还是.....................因为CF评测坏了,没有试过是否可过. 显然求\(\sum[i][0] - \sum[l][0] = \sum[i][1] - \sum[l][1]\) \(\sum[i][0] - \sum[l]...