From 84d0f094d87d31f7d4c3d1d0dd4f95c9ca6e8a7a Mon Sep 17 00:00:00 2001
From: Zengtudor <zengtudor@outlook.com>
Date: Tue, 8 Oct 2024 19:31:14 +0800
Subject: [PATCH] update

---
 src/P2822/P2822_prefix.cpp | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 src/P2822/P2822_prefix.cpp

diff --git a/src/P2822/P2822_prefix.cpp b/src/P2822/P2822_prefix.cpp
new file mode 100644
index 0000000..be7b80a
--- /dev/null
+++ b/src/P2822/P2822_prefix.cpp
@@ -0,0 +1,34 @@
+#include <iostream>
+#include <algorithm>
+
+using ull = unsigned long long;
+
+static constexpr size_t max_n {(size_t)2e3+5}; 
+
+ull k, c[max_n][max_n], prefix[max_n][max_n], t, n, m;
+
+static void init(){
+    c[0][0] = c[1][0] = c[1][1] = 1;
+    for(ull i {2};i<max_n;i++){
+        c[i][0]=1;
+        for(ull j{1};j<max_n;j++){
+            c[i][j] = (c[i-1][j-1] + c[i-1][j])%k;
+        }
+    }
+    for(ull i {2};i<max_n;i++){
+        for(ull j{1};j<=i;j++){
+            prefix[i][j] = prefix[i-1][j]+prefix[i][j-1]-prefix[i-1][j-1] + (c[i][j]==0?1:0);
+        }
+        prefix[i][i+1] = prefix[i][i];
+    }
+}   
+
+int main(){
+    std::cin>>t>>k;
+    init();
+    for(ull i {0};i<t;i++){
+        std::cin>>n>>m;
+        m = std::min(m,n);
+        std::cout<<(prefix[n][m])<<'\n';
+    }
+}
\ No newline at end of file