PAT甲级1018代码（仅DFS）

#include
#include
#include
using namespace std;
#define maxn 501
int C, N, S, M; int bikes[maxn]; int graph[maxn][maxn];
vector result;
struct road{
	vectorpath;
	int bring;
	int back;
	int length;
};
void dfs(int start,int final,struct road & r,int * isvisited) {
	if (start == final) {
		result.push_back(r);
		return;
	}
	for (int i = 0; i <= N; i++) {
		if (graph[start][i] != 0 && isvisited[i]==0) {
			r.path.push_back(i);
			isvisited[i] = 1;
			int bring_init = r.bring; int back_init = r.back;
			if (bikes[i] >= C / 2)
				r.back += bikes[i] - C / 2;
			else {
				if (C / 2 - bikes[i] >= r.back) {
					r.bring += C / 2 - bikes[i] - r.back;
					r.back = 0;
				}
				else {
					r.back = r.back-(C / 2 - bikes[i]);
				}
			}
			r.length += graph[start][i];
			dfs(i, final,r,isvisited);
			isvisited[i] = 0;
			r.bring =bring_init;
			r.back = back_init;
			r.length -= graph[start][i];
			r.path.pop_back();
		}
	}
	return;
}
bool compare(struct road r1, struct road r2) {
	if (r1.length < r2.length)
		return 1;
	else if (r1.length == r2.length)
		if (r1.bring < r2.bring)
			return 1;
		else if (r1.bring == r2.bring)
			if (r1.back < r2.back)
				return 1;
			else
				return 0;
		else
			return 0;
	else
		return 0;
}
int main() {
	cin >> C >> N >> S >> M;
	for (int i = 1; i <= N; i++) {
		cin >> bikes[i];
	}
	for (int i = 1; i <= M; i++) {
		int m, n;
		cin >> m >> n;
		cin >> graph[m][n];
		graph[n][m] = graph[m][n];
	}
	struct road r; r.path.push_back(0); r.bring = 0; r.back = 0; r.length = 0;
	int isvisited[maxn] = { 0 }; isvisited[0] = 1;
	dfs(0, S, r, isvisited);
	sort(result.begin(), result.end(), compare);
	cout << result[0].bring << " ";
	int size = result[0].path.size();
	for (int i = 0; i < size; i++) {
		cout << result[0].path[i];
		if (i != size - 1)
			cout << "->";
		else
			cout << " ";
	}
	cout << result[0].back;
	return 0;
}