Create 2019-B-C.cpp

segment tree

Author: tmp-coder

kick-start/2019-B-C.cpp

@@ -0,0 +1,92 @@
+#include<bits/stdc++.h>
+
+using namespace std;
+
+#define ms(x,v) memset(x,(v), sizeof(x))
+#define msn(x,v,n) memset(x,(v),sizeof(x[0]) * n)
+#define INF 0x3f3f3f3f
+
+typedef long long LL;
+
+
+const int MAXN = 100000 + 3;
+
+int a[MAXN];
+int S,n;
+
+struct SegTree{
+    int tree[MAXN<<2],lazy[MAXN<<2];
+    void clear(){
+        ms(tree,0);
+        ms(lazy,0);
+    }
+    void update(int val,int ul,int ur,int node=1,int l=1,int r=n){
+        if(ul > r || ur < l)return;
+        if(ul<=l && r <= ur){// contained
+            lazy[node] += val;
+            tree[node] += val;
+            return;
+        }
+        int lc = node <<1, rc = node <<1 |1;
+        int mid = (l+r) >>1;
+        update(val,ul,ur,lc,l,mid);
+        update(val,ul,ur,rc,mid+1,r);
+        tree[node] = max(tree[lc],tree[rc]) + lazy[node];
+    }
+
+    int Max(int ul,int ur,int node=1,int l=1,int r=n){
+        
+        if(ul>r || ur <l)return -INF;
+        if(ul <=l && r <=ur) return tree[node];
+        int mid = (l+r) >>1;
+        return max(Max(ul,ur,node<<1,l,mid),Max(ul,ur,node<<1|1,mid+1,r));
+    }
+};
+
+SegTree seg;
+
+int main(int argc, char const *argv[])
+{   
+    ios :: sync_with_stdio(0);
+    cin.tie(0);
+    std::cout.precision(8);
+    std::cout.setf( std::ios::fixed, std:: ios::floatfield );
+    int T;
+    cin >> T;
+
+    for(int t =1;  t <= T ; ++t)
+    {
+        
+        cin >>n >> S;
+        vector<int> pos[MAXN];
+        int ptr[MAXN];
+
+        for(int i=1 ; i<=n ; ++i){
+            cin >> a[i];
+            pos[a[i]].push_back(i);
+        }
+        for(int i=1 ; i <MAXN ; ++i)ptr[i] = pos[i].size()-1; // current access pos
+
+        seg.clear();
+        int ans =0;
+        for(int l = n ; l >0 ; --l){
+            seg.update(1,l,n);
+
+            int cur = a[l];
+            if(ptr[cur] + S <= pos[cur].size()-1){
+                int st = pos[cur][ptr[cur]+S];
+                seg.update(-(S+1),st,n);
+            }
+            if(ptr[cur] + S < pos[cur].size() -1){
+                int st = pos[cur][ptr[cur] +S +1];
+                seg.update(S,st,n);
+            }
+            ptr[cur]--;
+            ans = max(ans,seg.Max(1,n));
+        }
+
+        cout << "Case #"<<t << ": " << ans << "\n";
+    }
+
+    return 0;
+}