对图的深度优先遍历：
#include <iostream>
#define MAXE 1000
#define MAXN 100
#define INF 0x3f3f3f3f
using namespace std;
int g[MAXE][MAXN];
bool vis[MAXN] = { 0,1 };
int n, e, cnt;
void DFS(int cur) {
cout << cur << " ";
cnt++;
if (cnt == n)
return;
for (int i = 1; i <= n; ++i) {
if (g[cur][i] == 1 && !vis[i]) {
vis[i] = true;
DFS(i);
}
}
}
int main() {
cin >> n >> e; // 顶点数， 边数
for (int i = 1; i <= n; ++i)
for (int j = 1; j <= n; ++j)
g[i][j] = (i == j ? 0 : INF);
for (int i = 1; i <= e; ++i) {
int f, t;
cin >> f >> t;
g[t][f] = 1;
g[f][t] = 1;
}
DFS(1);
return 0;
}
对图的广度优先遍历：
#include <iostream>
#include <queue>
#define MAXN 100
#define MAXE 1000
#define INF 0x3f3f3f3f
using namespace std;
int g[MAXE][MAXN];
int n, e;
int main() {
cin >> n >> e; // 顶点数， 边数
for (int i = 1; i <= n; ++i)
for (int j = 1; j <= n; ++j)
g[i][j] = (i == j ? 0 : INF);
for (int i = 1; i <= e; ++i) {
int f, t;
cin >> f >> t;
g[f][t] = 1;
g[t][f] = 1;
}
queue<int> q;
bool vis[MAXN] = { 0,1 };
q.push(1);
while (!q.empty()) {
int cur = q.front();
for (int i = 1; i <= n; ++i) {
if (!vis[i] && g[cur][i] == 1) {
q.push(i);
vis[i] = true;
}
}
cout << cur << ' ';
q.pop();
}
return 0;
}
