Submission #379314

#	Time	Username	Problem	Language	Result	Execution time	Memory
379314		ChrisT	Salesman (IOI09_salesman)	C++17	100 / 100	1478 ms	65536 KiB

salesman

#include<bits/stdc++.h>
using namespace std;
const int MN = 5e5 + 5;
struct Seg {
	long long tree[MN << 1]; int n;
	Seg() {n = MN; memset(tree,-0x3f,sizeof tree);}
	void update (int i, long long v) {
		for (tree[i += n-1] = v; i > 1; i >>= 1)
			tree[i>>1] = max(tree[i],tree[i^1]);
	}
	long long query (int l, int r) {
		long long ret = -1e18;
		for (l += n-1, r += n; l < r; l >>= 1, r >>= 1) {
			if (l&1) ret = max(ret,tree[l++]);
			if (r&1) ret = max(ret,tree[--r]);
		}
		return ret;
	}
} segL, segR, segL2, segR2;
vector<array<int,2>> atT[MN];
int main () {
	int n,u,d,s;
	scanf ("%d %d %d %d",&n,&u,&d,&s);
	while (n--) {
		int t,l,m; scanf ("%d %d %d",&t,&l,&m);
		atT[t].push_back({l,m});
	}
	atT[MN-1].push_back({s,0});
	segL.update(s,d * s); segR.update(s,-u*s);
	for (int t = 1; t < MN; t++) if (!atT[t].empty()) {
		int m = (int)atT[t].size();
		vector<long long> dp1(m), dp2(m);
		sort(atT[t].begin(),atT[t].end());
		for (int i = 0; i < m; i++) {
			auto [l,c] = atT[t][i];
			dp1[i] = max(max(segL.query(1,l),segL2.query(1,l)) - d * l + c,max(segR.query(l,MN),segR2.query(l,MN)) + u * l + c);
			segL2.update(l,dp1[i] + d * l); segR2.update(l,dp1[i] - u * l);
		}
		for (int i = 0; i < m; i++) segL2.update(atT[t][i][0],-1e18), segR2.update(atT[t][i][0],-1e18);
		for (int i = m-1; i >= 0; i--) {
			auto [l,c] = atT[t][i];
			dp2[i] = max(max(segL.query(1,l),segL2.query(1,l)) - d * l + c,max(segR.query(l,MN),segR2.query(l,MN)) + u * l + c);
			segL2.update(l,dp2[i] + d * l); segR2.update(l,dp2[i] - u * l);
		}
		for (int i = 0; i < m; i++) {
			auto [l,c] = atT[t][i];
			segL2.update(l,-1e18); segR2.update(l,-1e18);
			segL.update(l,max(dp1[i],dp2[i]) + d * l); segR.update(l,max(dp1[i],dp2[i]) - u * l);
		}
		if (t + 1 == MN) return !printf ("%lld\n",dp1[0]);
	}
	return 0;
}

Compilation message (stderr)

salesman.cpp: In function 'int main()':
salesman.cpp:23:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   23 |  scanf ("%d %d %d %d",&n,&u,&d,&s);
      |  ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
salesman.cpp:25:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   25 |   int t,l,m; scanf ("%d %d %d",&t,&l,&m);
      |              ~~~~~~^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 100 / 100