Problem 给你一个2*n的矩阵,要求你用补充叠的矩阵去框,要求每个矩阵框中的数之和为0,问最多可以用几个矩阵. Solution 首先预处理出一个点到离它最近的一段和为0的区间的左端点 然后到这往前用记忆化搜索的方式DP就可以了 Notice 注意要记忆化 Code #include<map> #include<cmath> #include<cstdio> #include<cstring> #include<iostream> #inc…

题意: 一个由大写字母组成的长度为\(n(n \leq 75)\)的字符串,每次操作可以交换相邻位置的两个字母,求最少操作多少次使字符串中不出现子串VK 分析: VK之外的字母具体是什么,我们并不关心,所以可以统一设它们为X 设\(d(v,k,x,t)\)表示,已经确定前\(v\)个V,前\(k\)个K和前\(x\)个X为字符串的前\(v+k+x\)个字母,\(t\)取\(0\)或\(1\)表示第\(v+k+x\)个字母是否为V,最少需要操作多少次 在转移的时候可以选择后面的第\(v+1\)个V…

和FallDream组队瞎打一通--B两个人写的都挂了233,最后只剩下FallDream写的A和我写的C,最后我yy了个E靠谱做法结果打挂了,结束之后改了改就A了,难受. AC:AC Rank:180 Rating:2133-8->2125 A.Bear and Friendship Condition 题目大意:问一个无向图是否满足若a到b有边且b到c有边则a到c有边.(n<=150,000) 思路:判定每个连通块是不是团,不是则不满足,复杂度O(n). #include<cstdi…

771C Bear and Tree Jumps 大意: 给定树,每步能走到距离不超过$k$的任意点,记$f(s,t)$为$s$到$t$的最少步数,求$\sum\limits_{s<t}f(s,t)$ 对于路径$(u,v)$, 假设距离为$d$, 那么贡献为$\lceil\frac{d}{k}\rceil=\frac{d+(-d\text{%}k+k)\text{%}k}{k}$ 也就是说枚举每条边的贡献算出总路径长, 再$O(nk^2)$的$dp$求出多余部分, 最后除以$k$即为答案 #in…

Given N axis-aligned rectangles where N > 0, determine if they all together form an exact cover of a rectangular region. Each rectangle is represented as a bottom-left point and a top-right point. For example, a unit square is represented as [1,1,2,2…

Given a non-empty 2D matrix matrix and an integer k, find the max sum of a rectangle in the matrix such that its sum is no larger than k. Example: Given matrix = [ [1, 0, 1], [0, -2, 3] ] k = 2 The answer is 2. Because the sum of rectangle [[0, 1], […

An image is represented by a binary matrix with 0 as a white pixel and 1 as a black pixel. The black pixels are connected, i.e., there is only one black region. Pixels are connected horizontally and vertically. Given the location (x, y) of one of the…

Find the total area covered by two rectilinear rectangles in a2D plane. Each rectangle is defined by its bottom left corner and top right corner as shown in the figure. Assume that the total area is never beyond the maximum possible value of int. Cre…

Given a 2D binary matrix filled with 0's and 1's, find the largest rectangle containing all ones and return its area. 此题是之前那道的Largest Rectangle in Histogram 直方图中最大的矩形 的扩展,这道题的二维矩阵每一层向上都可以看做一个直方图,输入矩阵有多少行,就可以形成多少个直方图,对每个直方图都调用Largest Rectangle in Hist…

Given n non-negative integers representing the histogram's bar height where the width of each bar is 1, find the area of largest rectangle in the histogram. Above is a histogram where width of each bar is 1, given height = [2,1,5,6,2,3]. The largest…