给定数组 A=[1,n] (1≤n≤2×105)A = [1, n] ~ (1 \leq n \leq 2 \times 10^5)A=[1,n] (1≤n≤2×105)，求
∑1≤i≤n∑i≤j≤nmini≤k≤jai\sum_{1 \leq i \leq n} \sum_{i \leq j \leq n} \min_{i \leq k \leq j} a_i∑1≤i≤n∑i≤j≤nmini≤k≤jai
