modify code

Author: algorithmzuo

src/class183/Code01_Ratio2.java

@@ -0,0 +1,128 @@
+package class183;
+
+// 聪聪可可，C++版
+// 一共有n个节点，给定n-1条边，每条边有边权，所有节点组成一棵树
+// 如果点对(u, v)的简单路径权值和能被3整除，则称这个点对是合法的
+// 认为点对(x, x)的简单路径权值和是0，并且认为(x, y)和(y, x)是不同的点对
+// 打印(合法点对的数量 / 点对的总数量)的最简分数形式
+// 1 <= n、边权 <= 2 * 10^4
+// 测试链接 : https://www.luogu.com.cn/problem/P2634
+// 如下实现是C++的版本，C++版本和java版本逻辑完全一样
+// 提交如下代码，可以通过所有测试用例
+
+//#include <bits/stdc++.h>
+//
+//using namespace std;
+//
+//const int MAXN = 20001;
+//int n;
+//
+//int head[MAXN];
+//int nxt[MAXN << 1];
+//int to[MAXN << 1];
+//int weight[MAXN << 1];
+//int cntg;
+//
+//bool vis[MAXN];
+//int siz[MAXN];
+//
+//int cur[3];
+//int all[3];
+//
+//int gcd(int a, int b) {
+//    return b == 0 ? a : gcd(b, a % b);
+//}
+//
+//void addEdge(int u, int v, int w) {
+//    nxt[++cntg] = head[u];
+//    to[cntg] = v;
+//    weight[cntg] = w;
+//    head[u] = cntg;
+//}
+//
+//int getSize(int u, int fa) {
+//    siz[u] = 1;
+//    for (int e = head[u]; e > 0; e = nxt[e]) {
+//        int v = to[e];
+//        if (v != fa && !vis[v]) {
+//            siz[u] += getSize(v, u);
+//        }
+//    }
+//    return siz[u];
+//}
+//
+//int getCentroid(int u, int fa) {
+//    int half = getSize(u, fa) >> 1;
+//    bool find = false;
+//    while (!find) {
+//        find = true;
+//        for (int e = head[u]; e > 0; e = nxt[e]) {
+//            int v = to[e];
+//            if (v != fa && !vis[v] && siz[v] > half) {
+//                fa = u;
+//                u = v;
+//                find = false;
+//                break;
+//            }
+//        }
+//    }
+//    return u;
+//}
+//
+//void dfs(int u, int fa, int dis) {
+//    cur[dis % 3]++;
+//    for (int e = head[u]; e > 0; e = nxt[e]) {
+//        int v = to[e];
+//        if (v != fa && !vis[v]) {
+//            dfs(v, u, dis + weight[e]);
+//        }
+//    }
+//}
+//
+//int calc(int u) {
+//    int ans = 0;
+//    all[0] = all[1] = all[2] = 0;
+//    for (int e = head[u]; e > 0; e = nxt[e]) {
+//        int v = to[e];
+//        int w = weight[e];
+//        if (!vis[v]) {
+//            cur[0] = cur[1] = cur[2] = 0;
+//            dfs(v, u, w);
+//            ans += all[0] * cur[0] * 2 + all[1] * cur[2] * 2 + all[2] * cur[1] * 2 + cur[0] * 2;
+//            all[0] += cur[0];
+//            all[1] += cur[1];
+//            all[2] += cur[2];
+//        }
+//    }
+//    return ans;
+//}
+//
+//int solve(int u) {
+//    vis[u] = true;
+//    int ans = calc(u);
+//    for (int e = head[u]; e > 0; e = nxt[e]) {
+//        int v = to[e];
+//        if (!vis[v]) {
+//            ans += solve(getCentroid(v, u));
+//        }
+//    }
+//    return ans;
+//}
+//
+//int main() {
+//    ios::sync_with_stdio(false);
+//    cin.tie(nullptr);
+//    cin >> n;
+//    for (int i = 1, u, v, w; i < n; i++) {
+//        cin >> u >> v >> w;
+//        addEdge(u, v, w);
+//        addEdge(v, u, w);
+//    }
+//    int a = solve(getCentroid(1, 0)) + n;
+//    int b = n * n;
+//    int c = gcd(a, b);
+//    a /= c;
+//    b /= c;
+//    cout << a << "/" << b << '\n';
+//    return 0;
+//}