Given a m-by-n (0,1)-matrix, of all its submatrices of all 1's which is the largest? By largest we mean that the submatrix has the most elements. Input The input contains multiple test cases. Each test case begins with m and n (1 ≤ m, n ≤ 2000) on li…

Largest Submatrix of All 1’s Time Limit: 5000MS   Memory Limit: 131072K Total Submissions: 8551   Accepted: 3089 Case Time Limit: 2000MS Description Given a m-by-n (0,1)-matrix, of all its submatrices of all 1’s which is the largest? By largest we me…

Largest Rectangle in a Histogram http://poj.org/problem?id=2559 题意:给出若干宽度相同的矩形的高度(条形统计图),求最大子矩形面积 解题思路 单调栈的经典题(嫌弃字多可以先看后面的示例再来看这个思路) 显然,最终的子矩形高度一定和某一个矩形相等(反证).因此一个暴力的做法就是枚举每一个矩形,然后往两边扩散.在它左侧找到第一个高度比它小的,右侧也一样.则可以求出最大可扩散宽度,乘上高度即可以更新答案.复杂度O(n2) 如果说要优化刚才…

题目给一个01矩阵,求最大的1子矩阵. 先用dp预处理出每一行的每一列的1能向上按连续的1延伸多少,然后枚举每一行作为子矩阵的底,那样对于每一行的答案就是POJ2559这个经典问题了. #include<cstdio> #include<cstring> #include<algorithm> using namespace std; #define MAXN 2222 int stack[MAXN],top,l[MAXN],r[MAXN]; int calc(int…

[POJ 2559]Largest Rectangle in a Histogram Description A histogram is a polygon composed of a sequence of rectangles aligned at a common base line. The rectangles have equal widths but may have different heights. For example, the figure on the left s…

You are given an array a consisting of n elements. The imbalance value of some subsegment of this array is the difference between the maximum and minimum element from this segment. The imbalance value of the array is the sum of imbalance valuesof all…

https://codeforces.com/contest/1131/problem/G 题意 给你一排m个的骨牌(m<=1e7),每块之间相距1,每块高h[i],推倒代价c[i],假如\(abs(i-j)<h[i]\),那么向j方向推倒i,j也会倒,问选择任意数量骨牌向任意方向推到,使得全部骨牌都倒下的代价最小 题解 连锁反应可以用单调栈或者链表模拟 定义dp[i]为推倒a[i,m]的最小代价 对于每个i,有两种选择: 向左推:\(dp[l[i]+1]=min(dp[l[i]+1],dp[…

题目链接:http://poj.org/problem?id=2559 思路:单调栈 什么是单调栈? 单调栈,顾名思义,就是单调的栈,也就是占中存的东西永远是单调(也就是递增或递减)的 如何实现一个单调栈呢?过程很简单.假设栈中已有了若干单调递增的元素,此时我们又有了一个元素,如果这个元素比栈顶元素大,则直接入栈:反之,不断弹出当前元素,直到栈顶元素比之前小为止.(这里实现的是一个单调递增栈,递减栈和递增栈的过程一样) 为什么这道题可以用单调栈? 假设矩形的高度从左到右递增,那么答案是多少?显而…

Let's suppose you have an array a, a stack s (initially empty) and an array b (also initially empty). You may perform the following operations until both a and s are empty: Take the first element of a, push it into s and remove it from a (if a is not…

POJ 3494 Largest Submatrix of All 1’s Description Given a m-by-n (0,1)-matrix, of all its submatrices of all 1’s which is the largest? By largest we mean that the submatrix has the most elements. Input The input contains multiple test cases. Each tes…