Problem 给定一个长度为n的数字串,从中选取k个不重叠的子串(可以少选),将每个串求和si 求max|s1 - s2| + |s2 - s3| + ... + |sk - 1 - sk|(n <= 30000, k <= min(n, 200)) Solution 绝对值后的和,只和峰值和谷值的那些值有关(所以我们可以贪心峰值和谷值尽量多) 用f[i][j][k]表示前i个,分成j段,这个值在哪里(用k=0表示在谷值,k=1表示在谷值到峰值之间,k=2表示在峰值,k=3表示在峰值到谷值之…

题目大意: 给你一个数列,从中选出k个互不重叠的非空子串,定义s[i]为第i个子串的和,求|s[1]-s[2]|+|s[2]-s[3]|+...+|s[k-1]-s[k]|的最大值. 思路: 考虑将绝对值去掉,对于连续一段和单调的子串,结果只与其中峰值和谷值有关,中间的数会直接消掉. 我们用f[i][j][0..3]表示在第i个数时总共选了j和子串时的状态. 其中第三维为0时,表示当前子串为谷值. 第三维为2时,表示当前子串为峰值. 第三维为1时,表示当前子串在谷值到峰值之间. 第三维为3时,表…

我们肯定要一大一小间隔开来所以 把式子拆出来就是类似这样的形式 s1 - 2 * s2 + 2 * s3 + ...... + sn 然后把状态开成四个, 分别表示在顶部, 在底部, 在顶部到底部的中间, 在底部到顶部的中间. 反思一下为什么没写出来:我在考虑的时候 |s2 - s1| + |s3 - s2| + |s4 + s3| ,,, 我在想怎么把si 和 si + 1的大小关系的问题, 其实不用考虑, 因为我们求的是最大值, 所以对答案是没有影响的. #include<bits/stdc…

A Game题意:A,B各自拥有两堆石子,数目分别为n1, n2,每次至少取1个,最多分别取k1,k2个, A先取,最后谁会赢. 分析:显然每次取一个是最优的,n1 > n2时,先手赢. 代码: #include <bits/stdc++.h> #define pb push_back #define mp make_pair #define esp 1e-14 #define lson l, m, rt<<1 #define rson m+1, r, rt<<1…

Given an array nums and a target value k, find the maximum length of a subarray that sums to k. If there isn't one, return 0 instead. Example 1: Given nums = [1, -1, 5, -2, 3], k = 3, return 4. (because the subarray [1, -1, 5, -2] sums to 3 and is th…

Given an array of n positive integers and a positive integer s, find the minimal length of a subarray of which the sum ≥ s. If there isn't one, return 0 instead. For example, given the array [2,3,1,2,4,3] and s = 7,the subarray [4,3] has the minimal…

Find the contiguous subarray within an array (containing at least one number) which has the largest product. For example, given the array [2,3,-2,4],the contiguous subarray [2,3] has the largest product = 6. 这个求最大子数组乘积问题是由最大子数组之和问题演变而来,但是却比求最大子数组之和要复…

Find the contiguous subarray within an array (containing at least one number) which has the largest sum. For example, given the array [−2,1,−3,4,−1,2,1,−5,4],the contiguous subarray [4,−1,2,1] has the largest sum = 6. click to show more practice. Mor…

Problem: Given an array of n positive integers and a positive integer s, find the minimal length of a subarray of which the sum ≥ s. If there isn't one, return 0 instead. For example, given the array [2,3,1,2,4,3] and s = 7,the subarray [4,3] has the…

Find the contiguous subarray within an array (containing at least one number) which has the largest product. For example, given the array [2,3,-2,4],the contiguous subarray [2,3] has the largest product = 6. 子数组乘积最大 class Solution { public: int maxPr…