建图
邻接矩阵
#include <iostream>
#include <vector>
using namespace std;
// 点的最大数量
int MAX_N = 11;
// 邻接矩阵方式建图
vector<vector<int>> graph(MAX_N, vector<int>(MAX_N));
// 初始化，下标从 1 开始
void build(int n) {
for (int i = 1; i <= n; ++i)
for (int j = 1; j <= n; ++j)
graph[i][j] = 0;
}
// 有向图建图
void directedGraph(vector<vector<int>> &edges) {
for (const auto &edge: edges)
graph[edge[0]][edge[1]] = edge[2];
}
// 无向图建图
void undirectedGraph(vector<vector<int>> &edges) {
for (const auto &edge: edges) {
graph[edge[0]][edge[1]] = edge[2];
graph[edge[1]][edge[0]] = edge[2];
}
}
void traversal(int n) {
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= n; ++j)
cout << graph[i][j] << " ";
cout << endl;
}
}
int main() {
int n1 = 4;
vector<vector<int>> edges1 = {{1, 3, 6},
{4, 3, 4},
{2, 4, 2},
{1, 2, 7},
{2, 3, 5},
{3, 1, 1}};
build(n1);
directedGraph(edges1);
traversal(n1);
cout << endl;
int n2 = 5;
vector<vector<int>> edges2 = {{3, 5, 4},
{4, 1, 1},
{3, 4, 2},
{5, 2, 4},
{2, 3, 7},
{1, 5, 5},
{4, 2, 6}};
build(n2);
undirectedGraph(edges2);
traversal(n2);
}
邻接表
#include <iostream>
#include <vector>
#include <forward_list>
using namespace std;
// 点的最大数量
int MAX_N = 11;
// 邻接表方式建图
// 无权
// vector<forward_list<int>> graph(MAX_N);
// 带权
vector<forward_list<pair<int, int>>> graph(MAX_N);
// 初始化，下标从 1 开始
void build(int n) {
for (int i = 0; i <= n; ++i)
graph[i].clear();
}
// 有向图建图
void directedGraph(vector<vector<int>> &edges) {
for (const auto &edge: edges) {
// edge[0]: u edge[1]: v, u->v
// edge[2] 为权重
// forward_list 只能头插，使用 list 可以尾插
graph[edge[0]].emplace_front(make_pair(edge[1], edge[2]));
}
}
// 无向图建图
void undirectedGraph(vector<vector<int>> &edges) {
for (const auto &edge: edges) {
graph[edge[0]].emplace_front(make_pair(edge[1], edge[2]));
graph[edge[1]].emplace_front(make_pair(edge[0], edge[2]));
}
}
void traversal(int n) {
for (int i = 1; i <= n; ++i) {
cout << i << "(邻居、边权): ";
auto it = begin(graph[i]);
while (it != end(graph[i])) {
cout << "(" << (*it).first << ", " << (*it).second << ")";
it++;
}
cout << endl;
}
}
int main() {
int n1 = 4;
vector<vector<int>> edges1 = {{1, 3, 6},
{4, 3, 4},
{2, 4, 2},
{1, 2, 7},
{2, 3, 5},
{3, 1, 1}};
build(n1);
directedGraph(edges1);
traversal(n1);
cout << endl;
int n2 = 5;
vector<vector<int>> edges2 = {{3, 5, 4},
{4, 1, 1},
{3, 4, 2},
{5, 2, 4},
{2, 3, 7},
{1, 5, 5},
{4, 2, 6}};
build(n2);
undirectedGraph(edges2);
traversal(n2);
}
链式前向星
#include <iostream>
#include <vector>
using namespace std;
// 点的最大数量
int MAX_N = 11;
// 边的最大数量
// 只有链式前向星方式建图需要这个数量
// 注意如果无向图的最大数量是 m 条边，数量要准备 m*2
// 因为一条无向边要加两条有向边
int MAX_M = 11;
// 链式前向星方式建图
// 下标：顶点编号，值：该顶点第一条边的边号
vector<int> head(MAX_N);
// 下标：边号，值：下一条边的边号
vector<int> nxt(MAX_M);
// 下标：边号，值：去往的顶点编号
vector<int> to(MAX_M);
// 如果边有权重，那么需要这个数组
vector<int> weight(MAX_M);
// 边号计数，从 1 开始，0 表示没有边
int cnt;
// 初始化，下标从 1 开始
void build(int n) {
// 链式前向星清空
cnt = 1;
fill(head.begin(), head.end(), 0);
}
// 链式前向星加边，u->v，w 为权重
void addEdge(int u, int v, int w) {
// 记录权重
weight[cnt] = w;
// 边号为 cnt 的边作为新的头边，插入到旧的头边之前
nxt[cnt] = head[u];
to[cnt] = v;
head[u] = cnt;
cnt++;
}
// 有向图建图
void directedGraph(vector<vector<int>> &edges) {
for (const auto &edge: edges)
addEdge(edge[0], edge[1], edge[2]);
}
// 无向图建图
void undirectedGraph(vector<vector<int>> &edges) {
for (const auto &edge: edges) {
addEdge(edge[0], edge[1], edge[2]);
addEdge(edge[1], edge[0], edge[2]);
}
}
void traversal(int n) {
for (int i = 1; i <= n; ++i) {
cout << i << "(邻居、边权): ";
for (int ei = head[i]; ei > 0; ei = nxt[ei])
cout << "(" << to[ei] << "," << weight[ei] << ")";
cout << endl;
}
}
int main() {
int n1 = 4;
vector<vector<int>> edges1 = {{1, 3, 6},
{4, 3, 4},
{2, 4, 2},
{1, 2, 7},
{2, 3, 5},
{3, 1, 1}};
build(n1);
directedGraph(edges1);
traversal(n1);
cout << endl;
int n2 = 5;
vector<vector<int>> edges2 = {{3, 5, 4},
{4, 1, 1},
{3, 4, 2},
{5, 2, 4},
{2, 3, 7},
{1, 5, 5},
{4, 2, 6}};
build(n2);
undirectedGraph(edges2);
traversal(n2);
}
