Luogu1137 旅行计划 （拓扑排序）

每次入队时DP : \(f[v] = \max \{f[u] + 1\}\)

#include <iostream>

#include <cstdio>

#include <cstring>

#include <algorithm>

#include <cmath>

#define R(a,b,c) for(register int  a = (b); a <= (c); ++ a)

#define nR(a,b,c) for(register int  a = (b); a >= (c); -- a)

#define Max(a,b) ((a) > (b) ? (a) : (b))

#define Min(a,b) ((a) < (b) ? (a) : (b))

#define Fill(a,b) memset(a, b, sizeof(a))

#define Abs(a) ((a) < 0 ? -(a) : (a))

#define Swap(a,b) a^=b^=a^=b

#define ll long long

//#define ON_DEBUG

#ifdef ON_DEBUG

#define D_e_Line printf("\n\n----------\n\n")

#define D_e(x)  cout << #x << " = " << x << endl

#define Pause() system("pause")

#define FileOpen() freopen("in.txt","r",stdin);

#else

#define D_e_Line ;

#define D_e(x)  ;

#define Pause() ;

#define FileOpen() ;

#endif

struct ios{

    template<typename ATP>ios& operator >> (ATP &x){

        x = 0; int f = 1; char c;

        for(c = getchar(); c < '0' || c > '9'; c = getchar()) if(c == '-')  f = -1;

        while(c >= '0' && c <= '9') x = x * 10 + (c ^ '0'), c = getchar();

        x*= f;

        return *this;

    }

}io;

using namespace std;

const int N = 100007;

struct Edge{

	int nxt, pre;

}e[N << 1];

int head[N], cntEdge;

inline void add(int u, int v){

	e[++cntEdge] = (Edge){ head[u], v}, head[u] = cntEdge;

}

int ans[N];

int in[N];

int q[N], top;

int main(){

	FileOpen();

	int n, m;

	io >> n >> m;

	R(i,1,m){

		int u, v;

		io >> u >> v;

		add(u, v);

		++in[v];

	}

	R(i,1,n){

		if(!in[i]){

			ans[i] = 1;

			q[++top] = i;

		}

	}

	while(top){

		int u = q[top--];

		for(register int i = head[u]; i; i = e[i].nxt){

			int v = e[i].pre;

			--in[v];

			ans[v] = Max(ans[v], ans[u] + 1);

			if(!in[v]){

				q[++top] = v;

			}

		}

	}

	R(i,1,n){

		printf("%d\n", ans[i]);

	}

	return 0;

}

Luogu1137 旅行计划 （拓扑排序）的相关教程结束。