Intervals Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 26028   Accepted: 9952 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…

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 points and integers c1, ..., cn from the standard input, computes the minimal size of a set Z of…

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 points and integers c1, ..., cn from the standard input, computes the minimal size of a set Z of…

Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 28416   Accepted: 10966 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 points and…

题目链接 POJ1201 题解 差分约束 令\(a[i]\)表示是否选择\(i\),\(s[i]\)表示\(a[i]\)的前缀和 对\(s[i] \quad i \in [-1,50000]\)分别建立一个点 首先有 \[s[i] - s[i - 1] \ge 0\] \[s[i] - s[i - 1] \le 1\] 然后就是限制条件 \[s[b] - s[a - 1] \ge c\] 然后就没了 用\(spfa\)跑最长路 由于题目保证有解,所以不会存在正环 复杂度上界是\(O(nm)\)的…

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 points and integers c1, ..., cn from the standard input, computes the minimal size of a set Z of…

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 points and integers c1, ..., cn from the standard input, computes the minimal size of a set Z of integers wh…

与ZOJ2770一个建模方式,前缀和当作点. 对于每个区间[a,b]有这么个条件,Sa-Sb-1>=c,然后我就那样连边WA了好几次. 后来偷看数据才想到这题还有两个隐藏的约束条件. 这题前缀和表示的是区间内点存在的个数,因此: Si>=Si-1 Si-Si-1<=1 所以,差分约束系统的构图一定要考虑全面. #include<cstdio> #include<cstring> #include<queue> #include<algorithm…

转载请注明出处,谢谢:http://www.cnblogs.com/KirisameMarisa/p/4303365.html   ---by 墨染之樱花 题目链接:http://poj.org/problem?id=1201 题目描述:给出n个整数三元组(x,y,c),求一个整数集合Z,使其对每个前述三元组都满足在x与y之间(闭区间)的数的个数至少为c,求这个整数集合Z的最少有几个数 思路:利用差分约束系统求解.构造数列a1a2a3...an(其中ai只能为0或1,0表示i不在Z中,1表示i在…

差分约束经典题.设s[i]为前缀和,则有 s[i]-s[i-1]<=1 (i往i-1连-1的边) s[i]>=s[i-1] (i-1往i连0的边) s[b]-s[a-1]>=c (a-1往b连c的边) 最小值就改>=然后跑最长路 #include<iostream> #include<cstring> #include<cstdlib> #include<cstdio> #define ll long long using names…