动态规划

 https://leetcode.cn/problems/number-of-digit-one/ 

 https://leetcode.cn/problems/number-of-2s-in-range-lcci/ 

 https://leetcode.cn/problems/non-negative-integers-without-consecutive-ones/ 

 https://leetcode.cn/problems/numbers-at-most-n-given-digit-set/ 

 https://leetcode.cn/problems/numbers-with-repeated-digits/ 

 https://leetcode.cn/problems/digit-count-in-range/ 

 https://leetcode.cn/problems/find-all-good-strings/ 

 https://leetcode.cn/problems/count-special-integers/ 

 https://leetcode.cn/problems/maximum-sum-of-two-non-overlapping-subarrays/ 

数学

均值不等式

 https://leetcode.cn/problems/maximum-product-of-splitted-binary-tree/ 

位运算

 https://leetcode.cn/problems/maximum-xor-after-operations/ 

同余定理

 https://leetcode.cn/problems/subarray-sums-divisible-by-k/solution/he-ke-bei-k-zheng-chu-de-zi-shu-zu-by-leetcode-sol/ 

快速幂

 https://leetcode.cn/problems/count-good-numbers/

差分数组

 https://leetcode.cn/problems/divide-intervals-into-minimum-number-of-groups/  

贪心

 https://leetcode.cn/problems/reducing-dishes/ 

模拟

双堆模拟

 https://leetcode.cn/problems/meeting-rooms-iii/ 

数据结构

线段树

https://leetcode.cn/problems/meeting-rooms-iii/ 

字典树

 https://leetcode.cn/problems/sum-of-prefix-scores-of-strings/