Intervals Time Limit: 2000MS Memory Limit: 65536K Total Submissions: 30971 Accepted: 11990 Description You are given n closed, integer intervals [ai, bi] and n integers c1, ..., cn. Write a program that: reads the number of intervals, their end point…

Intervals Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 20779   Accepted: 7863 Description You are given n closed, integer intervals [ai, bi] and n integers c1, ..., cn.  Write a program that:  reads the number of intervals, their end…

做的第一道差分约束的题目,思考了一天,终于把差分约束弄懂了O(∩_∩)O哈哈~ 题意(略坑):三元组{ai,bi,ci},表示区间[ai,bi]上至少要有ci个数字相同,其实就是说,在区间[0,50000]上,每一个三元组表示[ai,bi]之间至少要标记ci个数字,问至少要标记多少个数字. 在学习差分约束的童鞋,建议看一下:09年姜碧野的<SPFA算法的优化及应用>,06年冯威的<浅析差分约束系统>,不过后者看起来较难搞懂,也可以看http://ycool.com/post/m2u…

关于差分约束详情可阅读:http://www.cppblog.com/menjitianya/archive/2015/11/19/212292.html 题意: 给定n个区间[L,R], 每个区间至少放w个球, 问最后整个区间最少要放多少个球. 分析: 假设d[i] 是 [1,i] 至少有多少个点被选中, 特殊地, d[0] = 0. 每个区间的描述可以转化为d[R] - d[L-1] >= w.(因为d[L]也要选中, 左闭右闭区间, 所以要减d[L-1])因为d[i]描述了一个求和函数,所…

POJ 1201 http://poj.org/problem?id=1201 题目大意: 有一个序列,题目用n个整数组合 [ai,bi,ci]来描述它,[ai,bi,ci]表示在该序列中处于[ai,bi]这个区间的整数至少有ci个.如果存在这样的序列,请求出满足题目要求的最短的序列长度是多少. 思路: 设s[i]为从1~i的整数个数. 这样对于区间[ a , b]显然有 S[b+1] - S[a] >=c[i] (为什么是b+1?因为闭区间b也要选上呀) 然后还有 0<= S[B+1]-S[…

Intervals Time Limit: 2000MS   Memory Limit: 65536KB   64bit IO Format: %lld & %llu Submit Status Description You are given n closed, integer intervals [ai, bi] and n integers c1, ..., cn. Write a program that: reads the number of intervals, their en…

题意:有n个区间[a,b],每个区间有一个值c.找一个集合中的元素使得每个区间至少有c个元素在这个集合中,问最小的集合大小. 思路:设d[i+1]表示0到i有多少个数在这个集合中,显然对于每个区间,d[b+1]-d[a]>=c,才能符合题目的要求.但是这样并不能使得所有集合都联系起来.继续挖掘条件,根据d[]的定义可得,0<=d[i+1]-d[i]<=1. 由此可得三个不等式: d[b+1]-d[a]>=c d[i+1]-d[i]>=0 d[i]-d[i+1]>=-1…

差分约束系统. #include<cstdio> #include<cstring> #include<cmath> #include<vector> #include<map> #include<queue> #include<algorithm> using namespace std; ; map<int, int> jz[maxn]; vector<int>ljb[maxn]; int di…

Description Once, in one kingdom, there was a queen and that queen was expecting a baby. The queen prayed: ``If my child was a son and if only he was a sound king.'' After nine months her child was born, and indeed, she gave birth to a nice son. Unfo…

Intervals Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 24099   Accepted: 9159 Description You are given n closed, integer intervals [ai, bi] and n integers c1, ..., cn. Write a program that: reads the number of intervals, their end po…