| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 73201 | Kmcode | Shortcut (IOI16_shortcut) | C++14 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include<bits/stdc++.h>
using namespace std;
//#include "shortcut.h"
vector<int> l;
vector<int> d;
#define MAX 1000002
long long int pref[MAX];
long long int bc[MAX];
long long int c;
int n;
long long int dp[MAX];
void init(){
for(int i=0;i<d.size();i++){
if(i)pref[i]=pref[i-1]+l[i-1];
pref[i]=max(pref[i],(long long int)d[i]);
}
for(int i=d.size()-1;i>=0;i--){
if(i!=d.size()-1){
bc[i]=bc[i+1]+l[i];
}
bc[i]=max(bc[i],(long long int)d[i]);
}
}
int pref_id(long long int z){
return upper_bound(pref,pref+n,z)-pref-1;
}
int bc_id(long long int z){
return lower_bound(bc,bc+n,z,greater<long long int>() )-bc;
}
long long int p[3002][3002];
void calc(){
for(int i=0;i<n;i++){
long long int len=0;
for(int j=i;j<n;j++){
if(i==j)p[i][j]=d[i];
else p[i][j]=len+d[i]+d[j];
if(j+1<n)len+=l[i];
}
}
for(int len=2;len<=n;len++){
for(int i=0;i<n;i++){
if(i+len<=n){
int j=i+len-1;
p[i][j]=max(p[i][j],p[i][j-1]);
p[i][j]=max(p[i][j],p[i+1][j]);
}
}
}
}
bool ok(long long int cost){
for(int i=0;i<n;i++){
if(pref[i]>cost)break;
if(p[0][i]>cost)break;
for(int j=n-1;j>=i;j--){
if(bc[j]>cost)continue;
if(p[j][n-1]>cost)continue;
if(max(i,pref_id(cost-pref[i]))>=min(j+1,bc_id(cost-pref[i]-c))-1){
if(max(i-1,pref_id(cost-pref[i]-c))+1>=min(i+1,bc_id(cost-pref[i]))){
return true;
}
}
}
}
return false;
}
long long find_shortcut(int n2, std::vector<int> l2, std::vector<int> d2, int c2)
{
n=d2.size();
c=c2;
l=l2;
d=d2;
n=d2.size();
init();
calc();
long long int mint=0;
long long int maxt=111111111111LL;
while(mint+1LL<maxt){
long long int mid=(mint+maxt)/2LL;
if(ok(mid)){
maxt=mid;
}
else{
mint=mid;
}
}
if(ok(mint))return mint;
return maxt;
}
int main()
{
int n, c;
assert(2 == scanf("%d%d", &n, &c));
std::vector<int> l(n - 1);
std::vector<int> d(n);
for (int i = 0; i < n - 1; i++)
assert(1 == scanf("%d", &l[i]));
for (int i = 0; i < n; i++)
assert(1 == scanf("%d", &d[i]));
long long t = find_shortcut(n, l, d, c);
printf("%lld\n", t);
return 0;
}