SGU 101 Domino(欧拉路径)

来源：互联网发布：网络盗窃40万判多少年编辑：程序博客网时间：2024/05/21 07:55

0-6作为结点，那么每个骨牌相当于一条无向边了

建图，进行欧拉路径判断，

然后dfs找出路径打印即可

代码：

#include <cstdio>#include <cstring>#include <vector>using namespace std;const int N = 7;int n;struct Edge {    int u, v, tp, id, vis;    Edge() {}    Edge(int u, int v, int tp, int id) {        this->u = u;        this->v = v;        this->tp = tp;        this->id = id;        this->vis = 0;    }}edge[205];int head[N], nxt[205], en;int deg[N];int judge() {    int cnt = 0, v;    for (int i = 0; i < 7; i++) if (deg[i]) v = i;    for (int i = 0; i < 7; i++) {        if (deg[i] % 2) {            cnt++;            v = i;        }    }    if (cnt == 0 || cnt == 2) return v;    return -1;}int ans[105][2], an;void add_edge(int u, int v, int tp, int id) {    edge[en] = Edge(u, v, tp, id);    nxt[en] = head[u];    head[u] = en++;}void dfs(int u) {    for (int i = head[u]; i + 1; i = nxt[i]) {        if (edge[i].vis) continue;        edge[i].vis = edge[i^1].vis = 1;        dfs(edge[i].v);        ans[an][0] = edge[i].id; ans[an][1] = !edge[i].tp; an++;    }}int main() {    while (~scanf("%d", &n)) {        int u, v;        memset(head, -1, sizeof(head));        en = 0;        memset(deg, 0, sizeof(deg));        for (int i = 1; i <= n; i++) {            scanf("%d%d", &u, &v);            deg[u]++; deg[v]++;            add_edge(u, v, 0, i);            add_edge(v, u, 1, i);        }        int s = judge();        if (s == -1) printf("No solution\n");        else {            an = 0;            dfs(s);            if (an != n) printf("No solution\n");            else {                for (int i = 0; i < an; i++)                    printf("%d %c\n", ans[i][0], ans[i][1] == 0 ? '+' : '-');            }        }    }    return 0;}

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