update

src/20241019/confess/confess_after.cpp

@@ -19,16 +19,33 @@ int main(){
         std::cin>>s;
         ll odd_add_num{}; //奇数+ -> -2
         ll even_sub_num{};//偶数- -> +2
+        /*
+            奇数->(bin*1)
+            偶数->(bin*0)
 
+            不坦白->
+                +1
+                -1
+                ->不论怎样，奇偶性质都会改变
+
+            坦白->
+                原本是'+'
+                    奇数(*1)->xor 1->*0 -2
+                    偶数(*0)->xor 1->*1 0
+                原本是'-'
+                    奇数(*1)->xor 1->*0 0
+                    偶数(*0)->xor 1->*1 +2
+                
+        */
         ll sum{};
         for(ll i{0};i<s.size();i++){
             if(s[i]=='+'){
-                if(i&1){
+                if(i&1){//奇数
                     ++odd_add_num;
                 }
                 sum++;
             }else{
-                if((i&1)==0){
+                if((i&1)==0){ // 偶数
                     even_sub_num++;
                 }
                 sum--;

src/P1351/P1351.cpp

@@ -0,0 +1,112 @@
+#include <algorithm>
+#include <iostream>
+#include <utility>
+#include <vector>
+
+using ll = long long;
+
+const ll max_n = 2e5+5;
+const ll MOD = 10007;
+ll n, w[max_n];
+
+std::vector<ll> next[max_n];
+ll brothers_from_father[max_n];
+
+ll ans_max,ans_sum;
+
+#ifdef ONLINE_JUDGE
+    #define DEBUG(code)
+#else
+    #define DEBUG(code)code
+#endif
+
+DEBUG(
+    template<class ...Args>
+    void debug(Args&&...args){
+        std::cout<<"[DEBUG]: ";
+        (std::cout<<...<<std::forward<Args>(args));
+        std::cout<<'\n';
+    }
+)
+
+void dfs(const ll now, const ll father,const ll grand_father){
+    if(father == -1){
+        for(const auto i:next[now]){
+            if(i==father)continue;
+            dfs(i, now,-1);
+        }
+        return;
+    }else if(grand_father == -1){
+        for(const auto i:next[now]){
+            if(i==father)continue;
+            dfs(i,now,father);
+        }
+        return;
+    }
+
+    DEBUG(
+        debug("args: ",now," ",father," ",grand_father);
+    )
+    if(!next[now].empty()){
+        for (const auto i: next[now]) {
+            if(i==father)continue;
+            dfs(i,now,father);
+        }
+    }
+    for(const auto i : next[father]){
+        if(i != now){
+            ans_max = std::max(ans_max, w[i]*w[now]);
+            DEBUG(
+                debug("update max ",ans_max);
+            )
+            DEBUG(
+                debug("brother: ",w[i],' ',w[now]);
+            )
+            brothers_from_father[father] = ((w[i]*w[now]) % MOD + brothers_from_father[father]) % MOD;
+        }
+    }
+    DEBUG(
+        debug(w[now],' ',w[grand_father]);
+    )
+    ans_max = std::max(ans_max, w[now] * w[grand_father]);
+    DEBUG(
+        debug("update max ",ans_max);
+    )
+    ans_sum  = (ans_sum + (w[now]*w[grand_father]) % MOD) % MOD;
+}
+
+int main(){
+    std::cin>>n;
+    for(ll i{1};i<n;i++){
+        ll a,b;
+        std::cin>>a>>b;
+        next[a].push_back(b);
+        next[b].push_back(a);
+    }
+    for(ll i{1};i<=n;i++){
+        std::cin>>w[i];
+    }
+    dfs(1, -1, -1);
+
+    for(ll i{1};i<=n;i++){
+        DEBUG(
+            debug("from brother ",i," add :",brothers_from_father[i]);
+        )
+        ans_sum  = (ans_sum + brothers_from_father[i]) % MOD;
+    }
+
+    std::cout<<ans_max<<' '<<(ans_sum) % MOD<<'\n';
+}
+
+/*
+
+4
+1 2
+2 3
+2 4
+1 2 3 4
+(3,4),(4,3),(1,3),(3,1),(1,4),(4,1)
+max = 12
+sum = 12+12+3+3+4+4 = 38
+
+*/