feat: 添加P1545.cpp解决动态规划问题

实现动态规划算法解决特定区间覆盖问题，计算最小覆盖次数。使用差分数组优化区间标记，并通过双重循环计算最优解。

src/11/18/P1545.cpp

@@ -0,0 +1,39 @@
+#include <algorithm>
+#include <cstdint>
+#include <cstdio>
+#include <iostream>
+#include <istream>
+#include <vector>
+using ll = int64_t;
+// #define printf
+const ll inf=1e9+7;
+ll n,l,a,b;
+std::vector<ll> v,dp,diff;
+
+int main(){
+    std::iostream::sync_with_stdio(false);
+    std::cin.tie(nullptr);
+
+    std::cin>>n>>l>>a>>b;
+    v.resize(l+1);dp.resize(l+1,inf);diff.resize(l+2);
+    for(ll i=1;i<=n;i++){
+        ll s,e;
+        std::cin>>s>>e;
+        v[s]++,v[e]--;
+        diff[e]++;
+    }
+    dp[0]=0;
+    for(ll i=1;i<=l;i++){
+        v[i]+=v[i-1];
+        for(ll j=a;j<=b&&i-j*2>=0;j++){
+            if(!v[i-j*2] || diff[i-j*2]==v[i-j*2-1]){
+                dp[i]=std::min(dp[i],dp[i-j*2]+1);
+            }
+        }
+        printf("now[%lld]=%lld\n",i,v[i]);
+        printf("dp[%lld]=%lld\n",i,dp[i]);
+        printf("diff[%lld]=%lld\n",i,diff[i]);
+        printf("\n");
+    }
+    std::cout<<dp[l]<<"\n";
+}