题目大意: 平面直角坐标系上有n个点,问以这n个点为顶点的不同的三角形的面积和是多少? 思路: 很容易想到一个O(n^3)的暴力,枚举三个点,用海龙公式求一下面积和即可,这样做是40分. 标算的复杂度是O(n^2 log n), 首先对所有的点按照位置的左右排序, 按顺序枚举每一个点i,并将其作为三角形的一个顶点. 对于顺序在i后面的点关于点i极角排序,并按照极角序枚举每一个点j. 三角形面积的两倍我们可以用叉积来求. 为了不枚举第三个顶点,我们可以算一下后缀和. 这题会爆double,由于小数…

From: http://www.geeksforgeeks.org/find-number-of-triangles-possible/ Given an unsorted array of positive integers. Find the number of triangles that can be formed with three different array elements as three sides of triangles. For a triangle to be…

[BZOJ1112][POI2008]砖块Klo 试题描述 N柱砖,希望有连续K柱的高度是一样的. 你可以选择以下两个动作 1:从某柱砖的顶端拿一块砖出来,丢掉不要了. 2:从仓库中拿出一块砖,放到另一柱.仓库无限大. 现在希望用最小次数的动作完成任务. 输入 第一行给出N,K. (1 ≤ k ≤ n ≤ 100000), 下面N行,每行代表这柱砖的高度.0 ≤ hi ≤ 1000000 输出 最小的动作次数 输入示例 输出示例 数据规模及约定 见"输入" 题解 在滑动的区间内维护中位…

1122: [POI2008]账本BBB Time Limit: 10 Sec  Memory Limit: 162 MBSubmit: 402  Solved: 202[Submit][Status][Discuss] Description 一个长度为n的记账单,+表示存￥1,-表示取￥1.现在发现记账单有问题.一开始本来已经存了￥p,并且知道最后账户上还有￥q.你要把记账单修改正确,使得 1:账户永远不会出现负数: 2:最后账户上还有￥q.你有2种操作: 1:对某一位取反,耗时x: 2:把…

1113: [Poi2008]海报PLA Time Limit: 10 Sec  Memory Limit: 162 MBSubmit: 1025  Solved: 679[Submit][Status][Discuss] Description N个矩形,排成一排. 现在希望用尽量少的矩形海报Cover住它们. Input 第一行给出数字N,代表有N个矩形.N在[1,250000] 下面N行,每行给出矩形的长与宽.其值在[1,1000000000]2 1/2 Postering Output…

1116: [POI2008]CLO Time Limit: 10 Sec  Memory Limit: 162 MBSubmit: 922  Solved: 514[Submit][Status][Discuss] Description Byteotia城市有n个 towns m条双向roads. 每条 road 连接 两个不同的 towns ,没有重复的road. 你要把其中一些road变成单向边使得:每个town都有且只有一个入度 Input 第一行输入n m.1 <= n<= 100…

1112: [POI2008]砖块Klo Time Limit: 10 Sec  Memory Limit: 162 MBSubmit: 1736  Solved: 606[Submit][Status][Discuss] Description N柱砖,希望有连续K柱的高度是一样的. 你可以选择以下两个动作 1:从某柱砖的顶端拿一块砖出来,丢掉不要了. 2:从仓库中拿出一块砖,放到另一柱.仓库无限大. 现在希望用最小次数的动作完成任务. Input 第一行给出N,K. (1 ≤ k ≤ n ≤…

1124: [POI2008]枪战Maf Time Limit: 10 Sec  Memory Limit: 162 MBSubmit: 617  Solved: 236[Submit][Status][Discuss] Description 有n个人,每个人手里有一把手枪.一开始所有人都选定一个人瞄准(有可能瞄准自己).然后他们按某个顺序开枪,且任意时刻只有一个人开枪.因此,对于不同的开枪顺序,最后死的人也不同. Input 输入n人数<1000000 每个人的aim Output 你要求最…

1123: [POI2008]BLO Time Limit: 10 Sec  Memory Limit: 162 MBSubmit: 1030  Solved: 440[Submit][Status][Discuss] Description Byteotia城市有n个 towns m条双向roads. 每条 road 连接 两个不同的 towns ,没有重复的road. 所有towns连通. Input 输入n<=100000 m<=500000及m条边 Output 输出n个数,代表如果把…

1121: [POI2008]激光发射器SZK Time Limit: 10 Sec  Memory Limit: 162 MBSubmit: 792  Solved: 653[Submit][Status][Discuss] Description 多边形相邻边垂直,边长为整数,边平行坐标轴.要在多边形的点上放一些激光发射器和接收器.满足下列要求: 1发射器和接收器不能放置在同一点: 2发射器发出激光可以沿壁反射,最终到达一个接收器: 3发射器只能沿角平分线发射激光.求:最多可放置多少对发射器…

Description It is always very nice to have little brothers or sisters. You can tease them, lock them in the bathroom or put red hot chili in their sandwiches. But there is also a time when all meanness comes back! As you know, in one month it is Chri…

Triangles Time Limit:1000MS     Memory Limit:64000KB     64bit IO Format:%lld & %llu Submit Status Practice ACdream 1067 Description 已知一个圆的圆周被  N 个点分成了 N 段等长圆弧,求任意取三个点,组成锐角三角形的个数. Input 多组数据. 每组数据一个N (N ≤  1000000). Output 对于每组数据,输出不同锐角三角形的个数. Sample…

You will be given N points on a circle. You must write a program to determine how many distinctequilateral triangles can be constructed using the given points as vertices.The gure below illustrates an example: (a) shows a set of points, determined by…

Fighting for Triangles 题目连接: http://codeforces.com/gym/100015/attachments Description Andy and Ralph are playing a two-player game on a triangular board that looks like the following: 1 2 3 4 5 7 8 6 9 10 11 13 14 16 17 12 15 18 At each turn, a playe…

C. Love Triangles Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/553/problem/C Description There are many anime that are about "love triangles": Alice loves Bob, and Charlie loves Bob as well, but Alice hates Charlie.…

D. Vanya and Triangles Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/552/problem/D Description Vanya got bored and he painted n distinct points on the plane. After that he connected all the points pairwise and saw that as…

Almost equilateral triangles It is easily proved that no equilateral triangle exists with integral length sides and integral area. However, the almost equilateral triangle 5-5-6 has an area of 12 square units. We shall define an almost equilateral tr…

Right triangles with integer coordinates The points P (x1, y1) and Q (x2, y2) are plotted at integer co-ordinates and are joined to the origin, O(0,0), to form ΔOPQ. There are exactly fourteen triangles containing a right angle that can be formed whe…

题目链接 原题: It turns out that 12 cm is the smallest length of wire that can be bent to form an integer sided right angle triangle in exactly one way, but there are many more examples. 12 cm: (3,4,5)24 cm: (6,8,10)30 cm: (5,12,13)36 cm: (9,12,15)40 cm: (…

Alyona and Triangles 题目连接: http://acm.hust.edu.cn/vjudge/contest/121333#problem/J Description You are given n points with integer coordinates on the plane. Points are given in a way such that there is no triangle, formed by any three of these n point…

1010: Triangles Time Limit: 2 Sec   Memory Limit: 128 MB Submit: 18   Solved: 8 Description You are given a figure consisting of n points in a 2D-plane and m segments connecting some of them. We guarantee that any two segments don’t share points exce…

Counting Triangles Problem Description Given an equilateral triangle with n thelength of its side, program to count how many triangles in it. Input The length n (n <= 500) of theequilateral triangle's side, one per line. process to the end of the fil…

枚举法: 枚举法是利用计算机速度快, 精度高的特点, 对要解决的问题所有可能情况进行霸道的, 一个不漏检验, 从中找出符合要求的答案. 特点: 1. 得到的结果一定正确. 2. 可能做了很多无用功,效率低下. 3. 一般会涉及到极值. 4. 数据量大的话可能造成时间崩溃. 结构: 循环结构. 基本思路: 1. 确定枚举对象, 枚举范围, 判定条件. 2. 枚举可能的解, 验证是否是问题的解. Vanya and Triangles : M - Vanya and Triangles Crawli…

1132: [POI2008]Tro Time Limit: 20 Sec  Memory Limit: 162 MBSubmit: 815  Solved: 211[Submit][Status] Description 平面上有N个点. 求出所有以这N个点为顶点的三角形的面积和 N<=3000 Input 第一行给出数字N,N在[3,3000] 下面N行给出N个点的坐标,其值在[0,10000] Output 保留一位小数,误差不超过0.1 Sample Input 5 0 0 1 2 0…

1116: [POI2008]CLO Time Limit: 10 Sec  Memory Limit: 162 MBSubmit: 565  Solved: 303[Submit][Status] Description Byteotia城市有n个 towns m条双向roads. 每条 road 连接 两个不同的 towns ,没有重复的road. 你要把其中一些road变成单向边使得:每个town都有且只有一个入度 Input 第一行输入n m.1 <= n<= 100000,1 <…

1123: [POI2008]BLO Time Limit: 10 Sec  Memory Limit: 162 MBSubmit: 614  Solved: 235[Submit][Status] Description Byteotia城市有n个 towns m条双向roads. 每条 road 连接 两个不同的 towns ,没有重复的road. 所有towns连通. Input 输入n<=100000 m<=500000及m条边 Output 输出n个数,代表如果把第i个点去掉,将有多…

Counting Triangles Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 2506    Accepted Submission(s): 1184 Problem Description Given an equilateral triangle with n the length of its side, program t…

Little Zu Chongzhi's Triangles Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 512000/512000 K (Java/Others)Total Submission(s): 743    Accepted Submission(s): 399 Problem Description Zu Chongzhi (429–500) was a prominent Chinese mathematicia…

Chef and The Right Triangles The Chef is given a list of N triangles. Each triangle is identfied by the coordinates of its three corners in the 2-D cartesian plane. His job is to figure out how many of the given triangles are right triangles. A right…

题目链接:12075 - Counting Triangles 题意:求n * m矩形内,最多能组成几个三角形 这题和UVA 1393类似,把总情况扣去三点共线情况,那么问题转化为求三点共线的情况,对于两点,求他们的gcd - 1,得到的就是他们之间有多少个点,那么情况数就能够求了,然后还是利用容斥原理去计数,然后累加出答案 代码: #include <stdio.h> #include <string.h> #include <algorithm> using nam…