update

src/P1330/P1330.cpp

@@ -0,0 +1,66 @@
+#include <iostream>
+#include <unistd.h>
+#include <vector>
+#include <bitset>
+#include <array>
+#include <queue>
+#include <algorithm>
+
+using ll = long long;
+static const ll max_n = 1e4+5;
+static auto &is = std::cin;
+static auto &os = std::cout;
+
+static ll n,m,u,v;
+std::vector<ll> map[max_n];
+std::bitset<max_n> vis;
+std::array<unsigned short,max_n> colors;
+struct Status{
+    ll now;
+    int color;
+};
+std::queue<Status> q;
+ll color_sum[3];
+
+void bfs(){
+    for(ll i{1};i<=n;i++){
+        if(vis[i])continue;
+        colors[i]=1;
+        color_sum[colors[i]]++;
+        vis[i]=true;
+        q.push({i,colors[i]});
+        while(!q.empty()){
+            const auto front = q.front();
+            q.pop();
+            
+            for(const auto i:map[front.now]){
+                const Status next_status{i,((front.color&1)+1)};
+                if(vis[next_status.now]){
+                    if(next_status.color!=colors[next_status.color]){
+                        os<<"Impossible\n";
+                        _exit(0);
+                    }
+                    continue;
+                }
+                colors[next_status.now]=next_status.color;
+                color_sum[colors[next_status.now]]++;
+                vis[next_status.now]=true;
+                q.push(next_status);
+            }
+        }
+    }
+    return;
+}
+int main(){
+    is>>n>>m;
+
+    for(ll i{0};i<m;i++){
+        is>>u>>v;
+        map[u].push_back(v);
+        map[v].push_back(u);
+    }
+
+    bfs();
+
+    os<<std::min(color_sum[1],color_sum[2])<<'\n';
+}