Merge pull request #1113 from AlgorithmWithGod/khj20006

[20251014] BOJ / P2 / 통행량 조사 / 권혁준

Author: ShinHeeEul

khj20006/202510/14 BOJ P2 통행량 조사.md

@@ -0,0 +1,99 @@
+```cpp
+#include <bits/stdc++.h>
+using namespace std;
+
+int N, M, cycCount = 0, E, R, r[200001]{}, ans[200001]{}, dep[200001]{}, s[200001]{}, par[200001][18]{}, cyc[200001][18]{};
+vector<vector<pair<int, int>>> v(200001);
+
+int f(int x) {return x==r[x] ? x : r[x]=f(r[x]);}
+
+int fillCycle(int n, int p, int t) {
+    if(n == t) return cyc[n][0] = 1;
+    for(auto [i,_]:v[n]) if(i != p) {
+        cyc[n][0] |= fillCycle(i,n,t);
+    }
+    return cyc[n][0];
+}
+
+void dfs(int n, int p, int d) {
+    par[n][0] = p, dep[n] = d;
+    for(auto [i,_]:v[n]) if(i != p) dfs(i,n,d+1);
+}
+
+int cle(int n, int p) {
+    for(auto [i,g]:v[n]) if(i != p) {
+        s[n] += cle(i,n);
+        if(cyc[i][0]) ans[g] += cycCount;
+        ans[g] += s[i];
+    }
+    return s[n];
+}
+
+int main(){
+    cin.tie(0)->sync_with_stdio(0);
+    
+    cin>>N>>M;
+    iota(r, r+N+1, 0);
+    for(int i=0,a,b;i<N;i++) {
+        cin>>a>>b;
+        int x = f(a), y = f(b);
+        if(x == y) {
+            fillCycle(a,0,b);
+            E = i;
+            R = a;
+        }
+        else {
+            v[a].emplace_back(b,i);
+            v[b].emplace_back(a,i);
+            r[x] = y;
+        }
+    }
+
+    dfs(R,0,0);
+    for(int k=1;k<18;k++) for(int i=1;i<=N;i++) {
+        par[i][k] = par[par[i][k-1]][k-1];
+        cyc[i][k] = cyc[i][k-1] + cyc[par[i][k-1]][k-1];
+    }
+
+    for(int x,y,c;M--;) {
+        cin>>x>>y>>c;
+        int a = x, b = y;
+        int cycSum = 0, diff = abs(dep[a]-dep[b]);
+        for(int k=0;k<18;k++) if(diff & (1<<k)) {
+            if(dep[a] < dep[b]) swap(a,b);
+            cycSum += cyc[a][k];
+            a = par[a][k];
+        }
+        for(int k=17;k>=0;k--) if(par[a][k] != par[b][k]) {
+            cycSum += cyc[a][k] + cyc[b][k];
+            a = par[a][k], b = par[b][k];
+        }
+        if(a != b) {
+            cycSum += cyc[a][0] + cyc[b][0];
+            a = par[a][0], b = par[b][0];
+        }
+        int lca = a;
+        cycSum += cyc[lca][0];
+
+        s[x] += c;
+        s[y] += c;
+        if(cycSum > 1) {
+            cycCount += c;
+            for(int k=17;k>=0;k--) {
+                if(!cyc[x][k]) x = par[x][k];
+                if(!cyc[y][k]) y = par[y][k];
+            }
+            s[x] -= c;
+            s[y] -= c;
+        }
+        else {
+            s[lca] -= 2*c;
+        }
+        
+    }
+    cle(R,0);
+    ans[E] += cycCount;
+    for(int i=0;i<N;i++) cout<<ans[i]<<'\n';
+
+}
+```