POJ-3159.Candies.(差分约束 + Spfa)】的更多相关文章

题意 编号为 1..N 的人, 每人有一个数; 需要满足 dj - di <= c 求1号的数与N号的数的最大差值.(略坑: 1 一定要比 N 大的...difference...不是"差别", 而是"做差"....) 思路 差分约束 差分约束顾名思义就是以"差值"作为约束条件的规划问题. 这个"差值"的特点使得这个问题可以转化为最短路问题(或最长路?) 由于SFPA(或Dijkstra)中的松弛操作: d[v] <…
分析:设每个人的糖果数量是a[i] 最终就是求a[n]-a[1]的最大值 然后给出m个关系 u,v,c 表示a[u]+c>=a[v] 就是a[v]-a[u]<=c 所以对于这种情况,按照u,v,c建单向边,一条从1到n的路径就是一个关于1和n的推广不等式a[n]-a[1]<=k(k为这条路的权) 所以找到所有不等式中最小k,就是求1到n的最短路,这就是差分约束 然后上代码: #include<cstdio> #include<cstring> #include&l…
Candies Time Limit: 1500MS   Memory Limit: 131072K Total Submissions: 22177   Accepted: 5936 Description During the kindergarten days, flymouse was the monitor of his class. Occasionally the head-teacher brought the kids of flymouse's class a large b…
Candies Time Limit: 1500MS   Memory Limit: 131072K Total Submissions: 40407   Accepted: 11367 Description During the kindergarten days, flymouse was the monitor of his class. Occasionally the head-teacher brought the kids of flymouse’s class a large…
Candies Time Limit: 1500MS   Memory Limit: 131072K Total Submissions: 28071   Accepted: 7751 Description During the kindergarten days, flymouse was the monitor of his class. Occasionally the head-teacher brought the kids of flymouse’s class a large b…
题目链接:http://poj.org/problem?id=3159 Candies Time Limit: 1500MS   Memory Limit: 131072K Total Submissions: 33576   Accepted: 9422 Description During the kindergarten days, flymouse was the monitor of his class. Occasionally the head-teacher brought th…
King Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 11946   Accepted: 4365 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 kin…
O - Layout(差分约束 + spfa) Like everyone else, cows like to stand close to their friends when queuing for feed. FJ has N (2 <= N <= 1,000) cows numbered 1-N standing along a straight line waiting for feed. The cows are standing in the same order as the…
POJ 3159 Candies (图论,差分约束系统,最短路) Description During the kindergarten days, flymouse was the monitor of his class. Occasionally the head-teacher brought the kids of flymouse's class a large bag of candies and had flymouse distribute them. All the kids…
题目链接http://poj.org/problem?id=3169 题目大意: 一些牛按序号排成一条直线. 有两种要求,A和B距离不得超过X,还有一种是C和D距离不得少于Y,问可能的最大距离.如果没有输出-1,如果可以随便排输出-2,否则输出最大的距离. 首先关于差分约束:https://blog.csdn.net/consciousman/article/details/53812818 了解了差分约束之后就知道该题典型的差分约束+spfa即可. #include<iostream> #i…