Create 17-Prize.cpp

Author: tmwilliamlin168

IOI/17-Prize.cpp

@@ -0,0 +1,61 @@
+#include "prize.h"
+#include <bits/stdc++.h>
+using namespace std;
+
+const int mxN=2e5;
+int n, a, ft[mxN+1];
+vector<int> v;
+
+void upd(int i) {
+	for(++i; i<=n; i+=i&-i)
+		++ft[i];
+}
+
+int qry(int i) {
+	int r=0;
+	for(; i; i-=i&-i)
+		r+=ft[i];
+	return r;
+}
+
+int dc(int l=0, int r=n-1, int sl=0, int sr=a) {
+	if(l>r)
+		return -1;
+	int ml=(l+r)/2, mr=ml;
+	vector<int> b;
+	for(; ml>=l; --ml) {
+		if(qry(r+1)-qry(l)>=sr-sl)
+			return -1;
+		if(qry(ml+1)-qry(ml))
+			continue;
+		b=ask(ml);
+		int c=b[0]+b[1];
+		if(!c)
+			return ml;
+		if(c>a) {
+			a=c;
+			for(int vi : v)
+				upd(vi);
+			v.clear();
+			return dc();
+		}
+		if(c==a) {
+			v.push_back(ml);
+			b[1]=b[0]+mr-ml;
+			break;
+		}
+		if(c<a)
+			upd(ml);
+	}
+	if(ml<l)
+		b[1]=sl+mr-ml;
+	int rl=dc(l, ml-1, sl, b[0]);
+	return ~rl?rl:dc(mr+1, r, b[1], sr);
+}
+
+int find_best(int N) {
+	n=N;
+	vector<int> b=ask(n-1);
+	a=b[0]+b[1];
+	return a?dc():n-1;
+}