Create L07-3.cpp

L07-3.cpp

@@ -0,0 +1,86 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+#define PUB push_back
+
+const double EPS = 1e-9;
+
+int N, M, K, ansId = 0;
+double sumE[5005];
+int dist[2][5005];
+vector<int>adjL[5005];
+
+int ways[2][5005];
+queue<int>q;
+
+void traverse(int a, int b, int id){
+	int jrk = 1,
+		cnt = 1,
+		child = 0;
+
+	ways[id][a] = 1; dist[id][a] = 0;
+	q.push(a);
+	while(!q.empty()){
+		if(cnt == 0){
+			jrk++;
+			swap(cnt, child);
+		}
+
+		int pos = q.front();
+		q.pop();
+
+		for(int nxt:adjL[pos]){
+			if(dist[id][nxt] == -1){
+				dist[id][nxt] = jrk;
+				ways[id][nxt] += ways[id][pos];
+				q.push(nxt);
+				child++;
+			}else if(dist[id][nxt] == jrk)
+				ways[id][nxt] += ways[id][pos];
+		}
+
+		cnt--;
+	}
+}
+
+int main(){
+	for(int i=0;i<5005;i++)
+		sumE[i] = 0;
+
+	cin >> N >> M;
+	for(int i=0;i<M;i++){
+		int u, v;
+		cin >> u >> v;
+
+		adjL[u].PUB(v);
+		adjL[v].PUB(u);
+	}
+
+	cin >> K;
+	for(int i=0;i<K;i++){
+		int a, b;
+		cin >> a >> b;
+
+		memset(ways, 0, sizeof ways);
+		memset(dist, -1, sizeof dist);
+
+		traverse(a, b, 0);
+		traverse(b, a, 1);
+
+		int tot_ways = ways[0][b],
+			tot_dist = dist[0][b];
+		for(int j=0;j<N;j++){
+			if(dist[0][j]+dist[1][j] == tot_dist){
+				double tmp = max(ways[0][j], ways[1][j]);
+				tmp /= (double) tot_ways;
+				sumE[j] += tmp;
+			}
+		}
+	}
+
+	for(int i=0;i<N;i++)
+		if(sumE[i]-sumE[ansId] > EPS)
+			ansId = i;
+
+	cout << ansId << endl;
+}