受前面一帖影响,看了下largest rectangle in histogram。divide and conquer的方
法很好理解,也很好code。但是linear的那个利用的stack的方法,主要思想是依次拿
array中的数与stack的top比较。但还是有些不太明白的地方,主要是如果histogram是
个倒序的,处理起来,貌似不对,例如,6,5,4,3,2,1。哪位大牛给讲讲,感激不尽
。
看讨论里 O(mn) 的解法都转化成了 histogram 下的最大矩形面积
其实如果读过《浅谈用极大化思想解决最大子矩形问题》这篇文章 里面介绍了一种悬
线法的 DP 时间复杂度是 O(mn) 的 原文图文讲解很好 实现起来也比 histogram 那个
容易一些
class Solution {
public:
int maximalRectangle(vector > &matrix) {
if (matrix.empty()) {
return 0;
}
int n = matrix[0].size();
vector H(n);
vector L(n);
vector R(n, n);
int ret = 0;
for (int i = 0; i < matrix.size(); ++i) {
int left = 0, right = n... 阅读全帖
On the Tools menu, click Data Analysis.
In the Analysis Tools box, click Histogram, and then click OK.
Under Input in the Input Range box, enter the cell reference for the range
of data you want to analyze.
Under Input in the Bin Range box, enter the cell reference to a range that
contains an optional set of boundary values that define bin ranges.
Note If you omit the bin range, the Histogram tool creates a set of evenly
distributed bins between the data's minimum and maximum values. However,
b
but how to distinguish different samples?
your way made the histograms mixed. Is there anyway to set the color or other
visual properties of histogram? the only parameters in command hist() is about
# of bins or center of bins? correct?
If you run the following code, you will see the disagreement between PROC
FREQ results and PROC UNIVARIATE (histogram) results on the SAME data.
On uniform data, PROC UNIVARIATE (histogram) generates two-level values --
Why??
Thanks.
【 以下文字转载自 JobHunting 讨论区 】
发信人: gandjmitbbs (Nothing), 信区: JobHunting
标 题: O(NlogN) largest rectangle in histogram
发信站: BBS 未名空间站 (Sun Dec 12 18:52:53 2010, 美东)
I'm not talking about the O(N) dp solution, but the O(NlogN) one based on
the order-statistic tree here: http://blog.csdn.net/arbuckle/archive/2006/05/06/710988.aspx
newbie question:
I read in a dataframe using R
some characteristics are related to sample
some characteristics are related patient, since patients have multiple
samples taken, patient_ID column has duplicates.
I wonder if there is an easy way to plot certain characteristics by
patient_ids, using histogram...
When plotting histogram in R, how exactly R is using breaks? can someone
help me if I understand correctly?
e.g.
breaks=c(0,1,2,3)
default is right= TURE, means the following three bins:
(0,1],(1,2],(2,3]
or
???
so if the entries is 0, they will not be counted?
if I want to include the 0 class in the first bin, I use right= FALSE, but
then the 3 is not included?
is there some way I can set a bin as just one point, e.g. 0 ?
thanks!
Hello,
The following code can pass the Leetcode test, if it ran separately.
But it can not pass the Leetcode online. Any problem? thanks.
class Solution {
public:
int largestAreaunderHistogramv(vector histogram, int size)
{
stack histindexlessthan;
int *area = new int[size];
int left = -1;
//get Li
for(int i=0; i
{
while(!histindexlessthan.empty())
{
if(histogram[i] <= histogram[histindexlessthan.top()])
... 阅读全帖
I can think of a two-pass approach.
First pass, Find the digits that do not have enough ones (i.e. bit positions
for which less than 50 inputs have a value of one in that bit position).
This first step is optional - even if you skip this step, you still only
need to accumulate ( 30 * 29 / 2 ) = 435 histogram bins.
// initialize
foreach bitIndex
accum [ bitIndex] = 0
// accumulate
foreach inputIndex
foreach bitIndex
accum [ bitIndex ] += input [ inputIndex ] . bit [ bitIndex ]
// Second ... 阅读全帖
刚学,请大家不要笑话。这个我完全不懂,
Compare the dotplot to a histogram of the data. (Select all that apply.)
a:Dotplots show the frequency of individual data values.
b:The raw data can be retrieved from the dotplot, but not the histogram.
c:The dotplot and histogram both show a greater density from 280 to 340.
d:Histograms show the frequency of individual data values.
E:The raw data can be retrieved from the histogram, but not the dotplot
bd, abcd, acd, acde, bcd, cde, ace, ce, ade, de我选了都不对,实在不知怎么搞
了,网上搜了也没有说明... 阅读全帖
刚把这题加进 OJ 里了,解法还挺多的。
brute force 的 O(N^2) 应该是过不了 large tests 的。
"Largest Rectangle in Histogram"
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 rectangle is shown in the shaded area, which has area = 10 unit.
For example,
Given height = [2,1,5,6,2,3],
return 10.
有道题目最近频繁出现,特地总结一下常规解法以及它的变体。有个经典变体我还没看
到一个很经典的答案,希望有人补上,呵呵。
1. The largest rectangle under a histogram http://www.informatik.uni-ulm.de/acm/Locals/2003/html/judge.html
Given: An integer array represents a histogram
Goal: Find the largest rectangle under the histogram.
Key observation: 输入为一个整数数组。如果某元素比它两边的邻居都小(比如Ai),
那么高度大于Ai的矩阵要么在该元素左边,要么在该元素右边,不可能穿过Ai。利用这
个性质,想办法遍历所有的矩形。
Complexity O(N) where N is the size of the given array.
2. Maximum subarray with all 1’s. (Generalization of problem 1)
http: