(-￣▽￣)-* //求一个集合,这个集合与任意一个区间的交集,需至少有两个数字 //贪心过程:按n个区间的最右值从小到大对区间进行排列, //集合首先取第一个区间的最右两个数字, //到第二个区间,判断集合里的数有没有在区间里 //没有的话,就从第二个区间的最右开始往左取(cnt=0取最后两个数,cnt=1取最后一个数) #include<iostream> #include<cstdio> #include<cstring> #include<algorith…

Chiaki has n intervals and the i-th of them is [li, ri]. She wants to delete some intervals so that there does not exist three intervals a, b and c such that a intersects with b, b intersects with c and c intersects with a. Chiaki is interested in th…

动态规划与贪心相关: {HDU}{4739}{Zhuge Liang's Mines}{压缩DP} 题意:给定20个点坐标,求最多有多少个不相交(点也不相交)的正方形 思路:背包问题,求出所有的正方形,然后求最多有多少个正方形不互相覆盖,这题真是神思路. {POJ}{3846}{Mountain Road} 题意:给定两个地点车的班次,路是双向单车道,求安排最短的时间 思路:对车次序列进行二维DP转移,转移的时候需要注意时刻的维护.这个题目的DP思路是正向DP,每次遍历到f[i][j]都需要更新…

Intervals 题目连接: http://codeforces.com/gym/100231/attachments Description 给你n个区间,告诉你每个区间内都有ci个数 然后你需要找一个最小的点集,使得满足这n个区间的条件 Input n 然后li,ri,ci Output 输出最小点集大小 Sample Input 5 3 7 3 8 10 3 6 8 1 1 3 1 10 11 1 Sample Output 6 Hint 题意 题解: 线段树+二分+贪心 首先我们贪心一…

Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 12123   Accepted: 5129 Description An integer interval [a,b], a < b, is a set of all consecutive integers beginning with a and ending with b. Write a program that: finds the minimal number…

Description Chiaki has n intervals and the i-th of them is [li, ri]. She wants to delete some intervals so that there does not exist three intervals a, b and c such that a intersects with b, b intersects with c and c intersects with a. Chiaki is inte…

Integer Intervals Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 12192   Accepted: 5145 Description An integer interval [a,b], a < b, is a set of all consecutive integers beginning with a and ending with b. Write a program that: finds t…

Chiaki has n intervals and the i-th of them is [li, ri]. She wants to delete some intervals so that there does not exist three intervals a, b and c such that aintersects with b, b intersects with c and c intersects with a. Chiaki is interested in the…

There is given the series of n closed intervals [ai; bi], where i=1,2,...,n. The sum of those intervals may be represented as a sum of closed pairwise non−intersecting intervals. The task is to find such representation with the minimal number of inte…

题目链接 http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemCode=3953 题意 给出N个区间,求去掉某些区间,使得剩下的区间中,任何的三个区间都不两两相交. 思路 将所有区间 以左端点为键值从小到大排序 然后三个三个一组 进行判断 如果 这三个中有两两相交的 那么就删去右端点最大的 因为这个区间对答案的贡献最小 然后三个区间当中没有两两相交的,那么下一次进来的区间就替换掉右端点最小的. AC代码 #include <cstdio…

Given a collection of intervals, merge all overlapping intervals. For example,Given [1,3],[2,6],[8,10],[15,18],return [1,6],[8,10],[15,18]. 题目的意思是将相交得区间合并,典型的贪心算法 首先将区间先按照start进行排序, 然后保存先前区间的start和end 如果当前的start > 先前的end,说明当前的区间与之前的区间不想交,则将先前的区间放入结果中…

Description There is given the series of n closed intervals [ai; bi], where i=1,2,...,n. The sum of those intervals may be represented as a sum of closed pairwise non−intersecting intervals. The task is to find such representation with the minimal nu…

Shopping 题目连接: http://codeforces.com/gym/100803/attachments Description Your friend will enjoy shopping. She will walk through a mall along a straight street, where N individual shops (numbered from 1 to N) are aligned at regular intervals. Each shop…

Four Operations Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 22    Accepted Submission(s): 12 Problem Description Little Ruins is a studious boy, recently he learned the four operations!Now h…

Gone Fishing Time Limit: 2000MS   Memory Limit: 32768K Total Submissions: 30281   Accepted: 9124 Description John is going on a fishing trip. He has h hours available (1 <= h <= 16), and there are n lakes in the area (2 <= n <= 25) all reachab…

开始前先讲几句废话:这个题我开始也没看懂,后来借助百度翻译,明白了大概是什么意思. 试题描述 输入一个n,然后输入n组数据,每个数据有两个数,代表这个闭区间是从几到几.然后看,如果任意两个闭区间有相重的地方,那么就把这两个闭区间合并,最后输出没有合并的闭区间. 试题描述正版 There is given the series of n closed intervals [ai; bi], where i=1,2,-,n. The sum of those intervals may be rep…

Intervals Time Limit: 1 Second      Memory Limit:65536 KB      Special Judge Chiaki has n intervals and thei-th of them is [li,ri]. She wants to delete some intervals so that there does not exist three intervalsa,b andc such thata intersects withb,b…

题目: 题目的大致意思是,给定n个闭区间,并且这个闭区间上的点都是整数,现在要求你使用最少的点来覆盖这些区间并且每个区间的覆盖的点的数量满足输入的要求点覆盖区间的数量. 输入: 第一行输入n,代表n个区间. 接下来的n行每行的第一个数代表区间起点,第二个数代表区间终点,第三个数代表这个区间必须要选取的点的数量. 输出: 输出最少的点的数量,这些最少的点要覆盖全部区间. 这个题是区间选点问题的一种变体,但是我们对于区间选点问题清楚之后那么这种题目也是一样解决的,只不过需要在某些地方特别处理一下.这…

Something happened in Uzhlyandia again... There are riots on the streets... Famous Uzhlyandian superheroes Shean the Sheep and Stas the Giraffe were called in order to save the situation. Upon the arriving, they found that citizens are worried about…

http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemId=5572 Intervals Time Limit: 1 Second      Memory Limit: 65536 KB      Special Judge Chiaki has n intervals and the i-th of them is [li, ri]. She wants to delete some intervals so that there do…

开始前先讲几句废话:这个题我开始也没看懂,后来借助百度翻译,明白了大概是什么意思. 试题描述 输入一个n,然后输入n组数据,每个数据有两个数,代表这个闭区间是从几到几.然后看,如果任意两个闭区间有相重的地方,那么就把这两个闭区间合并,最后输出没有合并的闭区间. 试题描述正版 There is given the series of n closed intervals [ai; bi], where i=1,2,…,n. The sum of those intervals may be rep…

1. Jump Game Given an array of non-negative integers, you are initially positioned at the first index of the array. Each element in the array represents your maximum jump length at that position. Determine if you are able to reach the last index. For…

题目: Problem Description This is a very simple question. There are N intervals in number axis, and M queries just like “QUERY(a,b)” indicate asking the maximum number of the disjoint intervals between (a,b) . Input There are several test cases. For ea…

Gone Fishing John is going on a fising trip. He has h hours available (1 ≤ h ≤ 16), and there are n lakes in the area (2 ≤ n ≤ 25) all reachable along a single, one-way road. John starts at lake 1, but he can finish at any lake he wants. He can only…

Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 13984   Accepted: 5943 Description An integer interval [a,b], a < b, is a set of all consecutive integers beginning with a and ending with b. Write a program that: finds the minimal number…

递归 Recursion:通过函数体来进行的循环. 思路简单但效率低(建立函数的副本,消耗大量时间和内存).能用迭代就不用递归.递推公式+递推终止条件. 计算n阶乘,递归实现 def Factorial(n): if n <= 1: # 终止条件 return 1 return n*Factorial(n-1) 层层深入再回溯: 递归的代码模板: def recursion(level, param1, param2, ...): # recursion terminator if level…

贪心基础 贪心(Greedy)常用于解决最优问题,以期通过某种策略获得一系列局部最优解.从而求得整体最优解. 贪心从局部最优角度考虑,只适用于具备无后效性的问题,即某个状态以前的过程不影响以后的状态.紧接下来的状态仅与当前状态有关.和分治.动态规划一样,贪心是一种思路,不是解决某类问题的具体方法. 应用贪心的关键,是甄别问题是否具备无后效性.找到获得局部最优的策略.有的问题比较浅显,例如一道找零钱的题目 LeetCode 860. Lemonade Change: // 860. Lemonad…

[44]Wildcard Matching [45]Jump Game II (2018年11月28日,算法群衍生题) 题目背景和 55 一样的,问我能到达最后一个index的话,最少走几步. 题解: [55]Jump Game (2018年11月27日,算法群) 给了一个数组nums,nums[i] = k 代表站在第 i 个位置的情况下, 我最多能往前走 k 个单位.问我能不能到达最后一个 index. 题解:虽然是贪心分类,我还是用dp解了.dp[i] 代表我能不能到达第 i 个位置. c…

题目如下: Given a collection of intervals, find the minimum number of intervals you need to remove to make the rest of the intervals non-overlapping. Note: You may assume the interval's end point is always bigger than its start point. Intervals like [1,2…

[452] Minimum Number of Arrows to Burst Balloons [Medium] 给一堆线段,使用最少的arrow,穿过所有的线段.陈题,第一条线段的终点. Input: [[10,16], [2,8], [1,6], [7,12]] Output: 2 Explanation: One way is to shoot one arrow for example at x = 6 (bursting the balloons [2,8] and [1,6]) a…