题意：给一个方阵，k个查询，每个查询求某个方阵的最大值和最小值之差。
思路：二维rmq.同时用到最大值和最小值的话可以把初始化写在一起。
1/* *********************************************** 2Author :111qqz 3Created Time :2016年05月16日 星期一 18时31分23秒 4File Name :code/poj/2019.cpp 5************************************************ */ 6 7#include <cstdio> 8 …
阅读更多题意：n位长的数字串（n<=1000),删掉m个（m<=n），使得剩下的数字串表示的数字最小。 忽略前导0.
思路：暴力搞就可以。要注意每位数字是有一定位置的范围的。比如当前是第i位数字，后面还要取n-m-i位数字，那么第i位数字最多只能取到第k位，k=m+i,因为这样才能保证后面还有n-m-i位数字。
阅读更多1636: [Usaco2007 Jan]Balanced Lineup
Time Limit: 5 Sec Memory Limit: 64 MB Submit: 680 Solved: 493 [Submit][Status][Discuss]
Description
For the daily milking, Farmer John’s N cows (1 <= N <= 50,000) always line up in the same order. One day Farmer John decides to organize a game of Ultimate Frisbee with …
阅读更多1689: [Usaco2005 Open] Muddy roads 泥泞的路
Time Limit: 5 Sec Memory Limit: 64 MB Submit: 311 Solved: 227 [Submit][Status][Discuss]
Description
Farmer John has a problem: the dirt road from his farm to town has suffered in the recent rainstorms and now contains (1 <= N <= 10,000) mud pools. Farmer John has a …
阅读更多1657: [Usaco2006 Mar]Mooo 奶牛的歌声
Time Limit: 5 Sec Memory Limit: 64 MB Submit: 634 Solved: 447 [Submit][Status][Discuss]
Description
Farmer John’s N (1 <= N <= 50,000) cows are standing in a very straight row and mooing. Each cow has a unique height h in the range 1..2,000,000,000 nanometers (FJ really is …
阅读更多1656: [Usaco2006 Jan] The Grove 树木
Time Limit: 5 Sec Memory Limit: 64 MB Submit: 143 Solved: 88 [Submit][Status][Discuss]
Description
The pasture contains a small, contiguous grove of trees that has no ‘holes’ in the middle of the it. Bessie wonders: how far is it to walk around that grove and get back to …
阅读更多1655: [Usaco2006 Jan] Dollar Dayz 奶牛商店
Time Limit: 5 Sec Memory Limit: 64 MB Submit: 353 Solved: 190 [Submit][Status][Discuss]
Description
Farmer John goes to Dollar Days at The Cow Store and discovers an unlimited number of tools on sale. During his first visit, the tools are selling variously for $1, $2, and $3. …
阅读更多1653: [Usaco2006 Feb]Backward Digit Sums
Time Limit: 5 Sec Memory Limit: 64 MB Submit: 349 Solved: 258 [Submit][Status][Discuss]
Description
FJ and his cows enjoy playing a mental game. They write down the numbers from 1 to N (1 <= N <= 10) in a certain order and then sum adjacent numbers to produce a new list …
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树边，前向边，后向边，横叉边，应该说，不是一个图本身有的概念，应该是图进行DFS时才有的概念。图进行DFS会得到一棵DFS树（森林），在这个树上才有了这些概念。对图进行DFS，可以从任意的顶点开始，遍历的方式也是多样的，所以不同的遍历会得到不同的DFS树，进而产生不同的树边，前向边，后向边，横叉边。所以这4种边，是一个相对的概念。 在图的遍历中，往往设置了一个标记数组vis的bool值来记录顶点是否被访问过。但有些时候需要改变vis值的意义。令vis具有3种值并表示3种不同含义 vis = 0,表示该顶点没没有被访问 vis = 1,表示该顶点已经被访问，但其子孙后代还没被访问完，也就没从该点返回 vis = …
阅读更多1652: [Usaco2006 Feb]Treats for the Cows
Time Limit: 5 Sec Memory Limit: 64 MB Submit: 290 Solved: 226 [Submit][Status][Discuss]
Description
FJ has purchased N (1 <= N <= 2000) yummy treats for the cows who get money for giving vast amounts of milk. FJ sells one treat per day and wants to maximize the money he …
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