From 22e2db73d94e20c9ba00f4af8cb179f4b5e9fbdc Mon Sep 17 00:00:00 2001
From: Zengtudor <Zengtudor@outlook.com>
Date: Fri, 29 Aug 2025 10:14:01 +0800
Subject: [PATCH] =?UTF-8?q?refactor(P4342.cpp):=20=E4=BC=98=E5=8C=96?=
 =?UTF-8?q?=E5=8A=A8=E6=80=81=E8=A7=84=E5=88=92=E5=AE=9E=E7=8E=B0=E5=B9=B6?=
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重构动态规划的实现方式，将原来的双重循环改为基于长度的遍历，提高代码可读性和效率。同时修复了最大值和最小值的计算逻辑，确保正确处理加法和乘法操作。添加结果收集和输出部分，完善程序功能。
---
 src/8/28/P4342.cpp | 67 ++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 56 insertions(+), 11 deletions(-)

diff --git a/src/8/28/P4342.cpp b/src/8/28/P4342.cpp
index 4c2433e..3e48a76 100644
--- a/src/8/28/P4342.cpp
+++ b/src/8/28/P4342.cpp
@@ -24,6 +24,7 @@ dpmin[i][j] =  1e9
 dp[i][i]=arr[i]
 
 */
+#include <algorithm>
 #include <cstdint>
 #include <iostream>
 #include <istream>
@@ -51,17 +52,61 @@ int main(){
         op[i+n]=op[i];
     }
     std::vector<std::vector<ll>> dpmax,dpmin;
-    for(ll s=1;s<n;s++){
-        ll e = s+n-1;
-        dpmax.clear();
-        dpmax.resize(n21,std::vector<ll>(n21,-1e9));
-        dpmin.clear();
-        dpmin.resize(n21,std::vector<ll>(n21,1e9));
-        for(ll i=s;i<=e;i++){
-            dpmax[i][i]=op[i][1];
-        }
-        for(ll i=s;i<=e;i++){
-            
+    dpmax.clear();
+    dpmax.resize(n21,std::vector<ll>(n21,-1e9));
+    dpmin.clear();
+    dpmin.resize(n21,std::vector<ll>(n21,1e9));
+    for(ll i=1;i<=2*n;i++){
+        dpmax[i][i]=op[i][1];
+        dpmin[i][i]=op[i][1];
+    }
+    for(ll len=2;len<=n;len++){
+        for(ll i=1;i<=2*n-len;i++){
+            ll j=i+len-1;
+            for(ll k=i;k<j;k++){
+                if(op[k+1][0]==add){ //注意是k+1
+                    dpmax[i][j]=std::max(
+                        dpmax[i][k]+dpmax[k+1][j],
+                        dpmax[i][j]
+                    );
+                    dpmin[i][j]=std::min(
+                        dpmin[i][k]+dpmin[k+1][j],
+                        dpmin[i][j]
+                    );
+                }else{
+                    dpmax[i][j]=std::max({
+                        dpmax[i][j],
+                        dpmax[i][k]*dpmax[k+1][j],
+                        dpmin[i][k]*dpmin[k+1][j],
+                        dpmax[i][k]*dpmin[k+1][j],
+                        dpmin[i][k]*dpmax[k+1][j]
+                    });
+                    dpmin[i][j]=std::min({
+                        dpmin[i][j],
+                        dpmax[i][k]*dpmax[k+1][j],
+                        dpmin[i][k]*dpmin[k+1][j],
+                        dpmax[i][k]*dpmin[k+1][j],
+                        dpmin[i][k]*dpmax[k+1][j]
+                    });
+                }
+            }
         }
     }
+    ll ans=-1e9;
+    std::vector<ll> edgs;
+    for(ll i=1;i<=n;i++){
+        ll nans=dpmax[i][i+n-1];
+        if(nans>ans){
+            ans=nans;
+            edgs.clear();
+            edgs.push_back(i);
+        }else if(nans==ans){
+            edgs.push_back(i);
+        }
+    }
+    std::cout<<ans<<"\n";
+    for(ll i:edgs){
+        std::cout<<i<<" ";
+    }
+    std::cout<<"\n";
 }
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