CF-Educational Codeforces Round 93 (Rated for Div. 2)-1398C. Good Subarrays【数学】
题目链接题意:给定一序列a1,a2,…,ana_1,a_2,\dots,a_na1,a2,…,an,若连续子序列al,al+1,al+2,…,ar−1,ara_l,a_{l+1},a_{l+2},\dots,a_{r-1},a_ral,al+1,al+2,…,ar−1,ar满足∑i=lrai=r−l+1\sum\limits_{i=l}^{r}a_i=r-l+1i=l∑rai=r−l+1,称为go