Codeforces
CF-2133 (Codeforces Round 1044, Div. 2) 题解
Codeforces
CF-2132 (Codeforces Round 1043, Div. 3) 题解
数学
用数学期望计算区间内整数各数位的和的和
Codeforces
CF-2131 (Codeforces Round 1042, Div. 3) 题解
Div. 3 其实挺好玩的
Codeforces
CF-2128 (Codeforces Round 1039, Div. 2) 题解
啃点难题
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