A11726 | Pathwalks
时间限制1s
内存限制256MB
通过 / 提交0/0
题目描述
You are given a directed graph with $n$ nodes and $m$ edges, with all edges having a certain weight.
There might be multiple edges and self loops, and the graph can also be disconnected.
You need to choose a path (possibly passing through same vertices multiple times) in the graph such that the weights of the edges are in strictly increasing order, and these edges come in the order of input. Among all such paths, you need to find the the path that has the maximum possible number of edges, and report this value.
Please note that the edges picked don't have to be consecutive in the input.
There might be multiple edges and self loops, and the graph can also be disconnected.
You need to choose a path (possibly passing through same vertices multiple times) in the graph such that the weights of the edges are in strictly increasing order, and these edges come in the order of input. Among all such paths, you need to find the the path that has the maximum possible number of edges, and report this value.
Please note that the edges picked don't have to be consecutive in the input.
输入格式
The first line contains two integers $n$ and $m$ ( $1<=n<=100000$ , $1<=m<=100000$ ) — the number of vertices and edges in the graph, respectively.
$m$ lines follows.
The $i$ -th of these lines contains three space separated integers $a_{i}$ , $b_{i}$ and $w_{i}$ ( $1<=a_{i},b_{i}<=n$ , $0<=w_{i}<=100000$ ), denoting an edge from vertex $a_{i}$ to vertex $b_{i}$ having weight $w_{i}$
$m$ lines follows.
The $i$ -th of these lines contains three space separated integers $a_{i}$ , $b_{i}$ and $w_{i}$ ( $1<=a_{i},b_{i}<=n$ , $0<=w_{i}<=100000$ ), denoting an edge from vertex $a_{i}$ to vertex $b_{i}$ having weight $w_{i}$
输出格式
Print one integer in a single line — the maximum number of edges in the path.
输入输出样例
输入 #1
3 3 3 1 3 1 2 1 2 3 2
输出 #1
2
输入 #2
5 5 1 3 2 3 2 3 3 4 5 5 4 0 4 5 8
输出 #2
3
The answer for the first sample input is $2$ : . Note that you cannot traverse  because edge  appears earlier in the input than the other two edges and hence cannot be picked/traversed after either of the other two edges.
In the second sample, it's optimal to pick $1$ -st, $3$ -rd and $5$ -th edges to get the optimal answer: .
In the second sample, it's optimal to pick $1$ -st, $3$ -rd and $5$ -th edges to get the optimal answer: .
C++ 编辑器
输入
输出
可保存默认模板；新题优先使用已保存模板。
当前快捷键仅展示，暂不支持修改。
- 撤销
Ctrl / ⌘ + Z - 重做
Ctrl / ⌘ + Y - 查找
Ctrl / ⌘ + F - 全选
Ctrl / ⌘ + A - 复制
Ctrl / ⌘ + C - 剪切
Ctrl / ⌘ + X - 粘贴
Ctrl / ⌘ + V - 自动排版
工具栏排版按钮 - 草稿保存
编辑时自动保存到本机
历史
提交记录
状态说明时间源码
AI
作答助手
你好，我是作答助手。可以问思路、复杂度、样例含义或代码报错原因；不会直接给出完整 AC 代码。
确定要清空代码吗？
提交通过
评测结果：Accepted