题目链接：Codeforces 459E Pashmak and Graph

题目大意：给定一张有向图，每条边有它的权值，要求选定一条路线，保证所经过的边权值严格递增，输出最长路径。

解题思路：将边依照权值排序，每次将同样权值的边同一时候增加，维护每一个点作为终止点的最大长度就可以。

#include <cstdio>

#include <cstring>

#include <algorithm>

using namespace std;

const int maxn = 3 * 1e5+5;

struct edge {

    int u, v, w;

}s[maxn];

bool cmp (const edge& a, const edge& b) {

    return a.w < b.w;

}

int n, m, d[maxn], f[maxn], val[maxn];

int main () {

    scanf("%d%d", &n, &m);

    memset(d, 0, sizeof(d));

    memset(f, 0, sizeof(f));

    memset(val, 0, sizeof(val));

    for (int i = 0; i < m; i++)

        scanf("%d%d%d", &s[i].u, &s[i].v, &s[i].w);

    sort(s, s + m, cmp);

    for (int i = 0; i < m; i++) {

        int j;

        for (j = i; s[j].w == s[i].w && j < m; j++);

        for (int k = i; k < j; k++)

            d[s[k].v] = max(d[s[k].v], f[s[k].u] + 1);

        for (int k = i; k < j; k++)

            f[s[k].v] = d[s[k].v];

        i = j - 1;

    }

    int ans = 0;

    for (int i = 1; i <= n; i++)

        ans = max(ans, f[i]);

    printf("%d\n", ans);

    return 0;

}