Codeforces 459E Pashmak and Graph(dp+贪心)

#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;
}