feat: 添加P8435.cpp和P4554.cpp解题代码

P4554.cpp实现了一个基于双端队列的BFS算法，用于解决网格图中的最短路径问题

src/10/2/P4554.cpp

@@ -0,0 +1,62 @@
+#include <cstdint>
+#include <cstdio>
+#include <deque>
+#include <iostream>
+#include <istream>
+using ll = int64_t;
+#define sl static inline
+const ll maxn = 505;
+ll n,m,x1,y1,x2,y2,inf=1e9+7;
+char c[maxn][maxn];
+ll ans[maxn][maxn];
+
+struct P{
+    ll x,y,s;
+};
+
+ll dis[4][2]={{1,0},{0,1},{-1,0},{0,-1}};
+
+sl int solve(){
+    std::cin>>n>>m;
+    if(n==0 && m==0)return 1;
+    for(ll i=0;i<n;i++){
+        for(ll j=0;j<m;j++){
+            std::cin>>c[i][j];
+            ans[i][j]=inf;
+        }
+    }
+    // printf("line = %d\n",__LINE__);
+    std::cin>>x1>>y1>>x2>>y2;
+    std::deque<P> dq;
+    dq.emplace_back(x1,y1,0);
+    while(dq.size()){
+        auto [x,y,s] = dq.front();
+        dq.pop_front();
+        for(ll i=0;i<4;i++){
+            ll nx=x+dis[i][0],ny=y+dis[i][1];
+            if(nx<0||nx>n-1||ny<0||ny>m-1)continue;
+            ll ns = s+(c[x][y]!=c[nx][ny]);
+            if(nx==x2&&ny==y2){
+                std::cout<<ns<<"\n";
+                return 0;
+            }
+            if(ns<ans[nx][ny]){
+                ans[nx][ny]=ns;
+                if(c[x][y]!=c[nx][ny]){
+                    dq.emplace_back(nx,ny,ns);
+                }else{
+                    dq.emplace_front(nx,ny,s);
+                }
+            }
+        }
+    }
+
+    return 0;
+}
+
+int main(){
+    std::iostream::sync_with_stdio(false);
+    std::cin.tie(nullptr);
+
+    while (!solve());
+}

src/10/2/P8435.cpp

@@ -0,0 +1,9 @@
+#include <cstdint>
+
+using ll = int64_t;
+
+
+
+int main(){
+    
+}