其他

The vast power system is the most complicated man-made system and the greatest engineering innovation in the 20th century. The following diagram shows a typical 14 bus power system. In real world, the power system may contains hundreds of buses and

題目連結：http://poj.org/problem?id=1112題目大意：有編號為1~n的n個人，給出每個人認識的人的編號，注意A認識B,B不一定認識A，讓你將所有的人分成兩組，要求每組的人相互認識，且兩組的人數要儘可能的接近。求出每組的人的編號。解題思路：圖論+背包（輸出物品）。相互認識的關係不好確定分組，如果轉換思路，考慮相互不認識的情況就簡單好多，如果A不認識B，且B不認識C，那麼A和C必須分到同一組裡。所以就想到了，連通分量的染色，相鄰的兩個染不同的顏色（0或1），每一個連通分量分

Problem DescriptionThe Joseph's problem is notoriously known. For those who are not familiar with the original problem: from among n people, numbered 1, 2, . . ., n, standing in circle every mth is going to be executed and only the life of the last

超級密碼Time Limit: 20000/10000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 1584    Accepted Submission(s): 478Problem

題目連結：http://poj.org/problem?id=1141題目大意：給一個由[,],{,}組成的字串序列，求增加最少的字元，使該序列能夠匹配，並輸出最後的方案。解題思路：區間dp.dp[i][j]表示從i~j

Sorting It All OutTime Limit: 1000MS Memory Limit: 10000KTotal Submissions: 23946 Accepted: 8280DescriptionAn ascending sorted sequence of distinct values is one in which some form of a less-than operator is used to order the elements from smallest

Problem DescriptionThe company "21st Century Fruits" has specialized in creating new sorts of fruits by transferring genes from one fruit into the genome of another one. Most times this method doesn't work, but sometimes, in very rare cases, a new

題目連結：http://acm.hdu.edu.cn/showproblem.php?pid=4704題目大意：給一個n,求出由1～n個正整數組成n的不同種數。解題思路：隔板法。由一個數組成的話為C(n-1,0),兩個的話為C(n-1,1),三個的C(n-1,2)....所以結果為2^(n-1).由於n很大有10^100000,顯然不能直接快速冪，這裡有兩種處理方式。1 因為2和M互質，所以由費馬小定理得2^(M-1)=1 mod (M).所以2^n=2^((M-1)*k+p)=2^p mod

You are given two positive integers A and B in Base C. For the equation:A=k*B+dWe know there always existing many non-negative pairs (k, d) that satisfy the equation above. Now in this problem, we want to maximize k.For example, A="123" and B="100",

D. Biridian Foresttime limit per test2 secondsmemory limit per test256 megabytesinputstandard inputoutputstandard outputYou're a mikemon breeder currently in the middle of your journey to become a mikemon master. Your current obstacle is go through

題目連結：http://acm.hdu.edu.cn/showproblem.php?pid=4705題目大意：給一棵樹，求三點不能通過簡單路徑到達的種數（也就是不在一條線上）。解題思路：如果枚舉Y形的話，要先枚舉一個點，然後在子樹中找三個點,這樣找有點麻煩，複雜度應該為o(n^2)。如果求補集，找三點在一條線的情況就好找了，枚舉中間的那個點還剩下兩個點，直接o(n)就可以解決（每次計算當前子樹到和前面子樹）。PS:樹上計數：遞迴+dp+數學。一般都能很好解決。遍曆樹只用記錄父親節點判有沒訪問即

Problem DescriptionIn this problem, we have f(n,x)=Floor[n/x]. Here Floor[x] is the biggest integer such that no larger than x. For example, Floor[1.1]=Floor[1.9]=1, Floor[2.0]=2.You are given 3 positive integers n, L and R. Print the result of

E. Graph Reconstructiontime limit per test3 secondsmemory limit per test256 megabytesinputstandard inputoutputstandard outputI have an undirected graph consisting of n nodes, numbered 1 through n. Each node has at most two incident edges. For each

題目連結：http://codeforces.com/problemset/problem/337/D題目大意：給一棵樹，m個點，一個距離d，求有多少個點A,使得A到所有的m個點距離都不超過d.解題思路：樹形dp.有兩種方法可以解：1、類似於樹的直徑的求法，先以任意一點作為樹根，找到距離該點最遠的m中的A點（A點一定是m個點中距離相距最遠的兩點的一個端點），然後以A點作為樹根，依次計算各點到A點的最短距離d1[]，並找到距離最遠的m中的點B點,然後以B點為樹根，依次找到各點到B點的距離d2[].

題目連結：http://acm.hdu.edu.cn/showproblem.php?pid=4597題目意思：給兩堆數，A和B兩個人比賽，每次每人只能拿每堆的第一個或最後一個數，兩人均表現最佳，問A開始，他能拿到的數和最大是多少。解題思路：對抗搜尋，或dp.一拿到這道題就知道是記憶化搜尋，但狀態轉移，一直沒弄很清楚，卡了很久，最後由於水題看錯了，搞了幾個小時。。。。最後就沒最後了。。。開始dp一直搞成5維的，最後一維表示誰先開始。但是這樣轉移的時候不能直接加進去，因為後面是另外一個人的。最後聽

Problem DescriptionOverpower often go to the playground with classmates. They play and chat on the playground. One day, there are a lot of stars in the sky. Suddenly, one of Overpower’s classmates ask him: “How many acute triangles whose inner

Frame StackingTime Limit: 1000MS Memory Limit: 10000KTotal Submissions: 3684 Accepted: 1223DescriptionConsider the following 5 picture frames placed on an 9 x 8 array. ........ ........ ........ ........ .CCC....EEEEEE.. ........ ........ ..BBBB..

Problem DescriptionNow you are given one non-negative integer n in 10-base notation, it will only contain digits ('0'-'9'). You are allowed to choose 2 integers i and j, such that: i!=j, 1≤i<j≤|n|, here |n| means the length of n’s 10-base

HighwaysTime Limit: 1000MS Memory Limit: 10000KTotal Submissions: 7187 Accepted: 1961 Special JudgeDescriptionThe island nation of Flatopia is perfectly flat. Unfortunately, Flatopia has a very poor system of public highways. The Flatopian

Problem DescriptionIgnatius被魔王抓走了,有一天魔王出差去了,這可是Ignatius逃亡的好機會.魔王住在一個城堡裡,城堡是一個A*B*C的立方體,可以被表示成A個B*C的矩陣,剛開始Ignatius被關在(0,0,0)的位置,離開城堡的門在(A-1,B-1,C-1)的位置,現在知道魔王將在T分鐘後回到城堡,Ignatius每分鐘能從一個座標走到相鄰的六個座標中的其中一個.現在給你城堡的地圖,請你計算出Ignatius能否在魔王回來前離開城堡(只要走到出口就算離開城堡,