Given two integers n and k, find how many different arrays consist of numbers from 1 to n such that there are exactly k inverse pairs. We define an inverse pair as following: For ith and jth element in the array, if i < j and a[i] > a[j] then it's a…

Given two integers n and k, find how many different arrays consist of numbers from 1 to n such that there are exactly k inverse pairs. We define an inverse pair as following: For ith and jthelement in the array, if i < j and a[i] > a[j] then it's an…

Given two integers n and k, find how many different arrays consist of numbers from 1 to n such that there are exactly k inverse pairs. We define an inverse pair as following: For ith and jth element in the array, if i < j and a[i] > a[j] then it's a…

https://leetcode.com/problems/k-inverse-pairs-array/description/ [题意] 给定n和k,求正好有k个逆序对的长度为n的序列有多少个,0<=k<=1000, 1<=n<=1000,答案模1e9+7 [思路] dp[i][j]表示正好有j个逆序对的长度为i的序列的方案数,最终我们要求的就是dp[n][k] 考虑dp[i+1][j]和dp[i][j]的关系,长度为i+1的序列相当于在长度为i的序列中插入一个数,那么有 xxx…

Given two integers n and k, find how many different arrays consist of numbers from 1 to n such that there are exactly k inverse pairs. We define an inverse pair as following: For ith and jth element in the array, if i < j and a[i] > a[j] then it's a…

Follow up for "Search in Rotated Sorted Array":What if duplicates are allowed? Would this affect the run-time complexity? How and why? Write a function to determine if a given target is in the array. 这个和前面的一个不一样就在于可能会有重复的数字,那么判断的时候就应该注意了,遇到start…

Given a sorted array of integers nums and integer values a, b and c. Apply a function of the form f(x) = ax2 + bx + c to each element x in the array. The returned array must be in sorted order. Expected time complexity: O(n) Example: nums = [-4, -2,…

Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array.Note:You may assume that nums1 has enough space (size that is greater or equal to m + n) to hold additional elements from nums2. The number of elements initia…

这道题是LeetCode里的第88道题. 题目描述: 给定两个有序整数数组 nums1 和 nums2,将 nums2 合并到 nums1 中,使得 num1 成为一个有序数组. 说明: 初始化 nums1 和 nums2 的元素数量分别为 m 和 n. 你可以假设 nums1 有足够的空间(空间大小大于或等于 m + n)来保存 nums2 中的元素. 示例: 输入: nums1 = [1,2,3,0,0,0], m = 3 nums2 = [2,5,6], n = 3 输出: [1,2,2,…

You are given two integer arrays nums1 and nums2 sorted in ascending order and an integer k. Define a pair (u,v) which consists of one element from the first array and one element from the second array. Find the k pairs (u1,v1),(u2,v2) ...(uk,vk) wit…