feat: 添加P1004.cpp解决动态规划路径问题

实现动态规划算法解决网格路径最大值问题，包含两次遍历计算最优路径和分数累加

src/9/6/P1004.cpp

@@ -0,0 +1,68 @@
+#include <cstdint>
+#include <iostream>
+#include <istream>
+#include <tuple>
+#include <vector>
+using ll = int64_t;
+
+ll n,x,y,z,ans0;
+struct DP{
+    ll val;
+    ll x,y;
+};
+
+int main(){
+    std::iostream::sync_with_stdio(false);
+    std::cin.tie(nullptr);
+
+    std::cin>>n;
+    std::vector<std::vector<ll>> map(n+1,std::vector<ll>(n+1));
+    std::vector<std::vector<DP>> dp(n+1,std::vector<DP>(n+1));
+    do {
+        std::cin>>x>>y>>z;
+        map[x][y]=z;
+    }while (x|y|z);
+    for(ll i=1;i<=n;i++){
+        for(ll j=1;j<=n;j++){
+            if(dp[i][j].val<dp[i][j-1].val+map[i][j]){
+                dp[i][j].val = dp[i][j-1].val + map[i][j];
+                dp[i][j].x = i;
+                dp[i][j].y = j-1;
+            }
+            if(dp[i][j].val<dp[i-1][j].val+map[i][j]){
+                dp[i][j].val = dp[i-1][j].val + map[i][j];
+                dp[i][j].x = i-1;
+                dp[i][j].y = j;
+            }
+        }
+    }
+    ans0=dp[n][n].val;
+    map[n][n]=0;
+    while(true){
+        static ll nx=dp[n][n].x,ny=dp[n][n].y;
+        if((nx|ny)==0){
+            break;
+        }
+        map[nx][ny]=0;
+        auto[val,x,y] = dp[nx][ny];
+        nx=x,ny=y;
+    }
+    dp.clear();
+    dp.resize(n+1,std::vector<DP>(n+1));
+    for(ll i=1;i<=n;i++){
+        for(ll j=1;j<=n;j++){
+            if(dp[i][j].val<dp[i][j-1].val+map[i][j]){
+                dp[i][j].val = dp[i][j-1].val + map[i][j];
+                dp[i][j].x = i;
+                dp[i][j].y = j-1;
+            }
+            if(dp[i][j].val<dp[i-1][j].val+map[i][j]){
+                dp[i][j].val = dp[i-1][j].val + map[i][j];
+                dp[i][j].x = i-1;
+                dp[i][j].y = j;
+            }
+        }
+    }
+    // std::cout<<dp[n][n].val<<"\n";
+    std::cout<<dp[n][n].val+ans0<<"\n";
+}