Submission #25536

#	Time	Username	Problem	Language	Result	Execution time	Memory
25536		mohammad_kilani	Shortcut (IOI16_shortcut)	C++14	97 / 100	1219 ms	33720 KiB

shortcut

#include "shortcut.h"
#include <bits/stdc++.h>
using namespace std;

long long sum[300010];
int idx1,idx2;


long long find_shortcut(int n, std::vector<int> l, std::vector<int> d, int c)
{
	for(int i=1;i<n;i++)
		sum[i] = sum[i-1] + l[i-1];
    long long left = 0 , right = 1e18;
    long long ans = 0;
    long long mx = d[0];
    int last = 0 ;
    idx1 = 0;

    for(int i=1;i<n;i++){
        long long dis = sum[i] - sum[last] +d[i] + d[last] ;
        if(dis > mx){
            mx = dis ;
            idx1 = last;
            idx2 = i ;
        }
        if(d[i] > sum[i] - sum[last] + d[last])
            last = i ;
    }
    right = mx;
    ans = mx;
    last =0  ;
    mx = d[0] ;
    for(int i=1;i<=idx1;i++){
    	long long dis = sum[i] - sum[last] + d[i] + d[last];
    	if(dis > mx){
    		mx = dis;
    	}
    	if(d[i] > sum[i] - sum[last] + d[last])
    		last = i;
    }
    last = idx2;
    mx = max(mx,(long long)d[last]);
    for(int i=idx2+1;i<n;i++){
    	long long dis = sum[i] - sum[last] + d[i] + d[last];
    	if(dis > mx){
    		mx = dis;
    	}
    	if(d[i] > sum[i] - sum[last] + d[last])
    		last = i;
    }
    left = mx;
    while(right >= left){
        long long mid=(left+right)/2;
        long long mx1 = 0 ;
        int idx3 = idx1;
        long long mx2= 0;
        int idx4 = idx2;
        for(int i=idx1+1;i<idx2;i++){
                long long dis = sum[i] - sum[idx1] + d[i] + d[idx1];
                long long dis2 = sum[idx2] - sum[i] + d[idx2] + d[i];
                if(dis > mid){
                    if(dis2 > mx2)
                    {
                        mx2 = dis2 ;
                        idx4= i ;
                    }
                }
                if(dis2 > mid){
                    if(dis > mx1){
                        mx1 = dis ;
                        idx3 = i;
                    }
                }
        }
        bool can = 1 ;
        int idx5 = idx1;
        int idx6 = idx2;
        long long mn = 1e18;
        for(int i=idx1;i<=idx3;i++){
        	long long dis = max((long long)(sum[i] - sum[idx1] + (long long)d[idx1]),(long long)(sum[idx3] - sum[i] + (long long)d[idx3])) + (long long)c + d[idx2];
        	if(dis > mid)
        		continue;
        	long long cur = mid - dis;
        	int j = lower_bound(sum,sum+n,sum[idx2]-cur) - sum;
        	if(j < idx4)
        		j = idx4;
        	long long dis2 = sum[i] - sum[idx1] + d[idx1] + c + sum[j] - sum[idx4] + d[idx4];
        	if(dis2 > mid)
        		continue;
            long long dis4 = sum[idx3] - sum[i] + sum[j] - sum[idx4];
            if(dis4 < mn){
                    mn = dis4;
                    idx5 = i;
                    idx6 = j;
            }
        }
        long long dis = max(sum[idx5] - sum[idx1] + d[idx1],sum[idx3] - sum[idx5] + d[idx3]) + c + sum[idx2] - sum[idx6] + d[idx2];
        if(dis > mid)
        	can = false;
        long long dis2 = max(sum[idx2] - sum[idx6] + d[idx2],sum[idx6] - sum[idx4] + d[idx4]) + c + sum[idx5] - sum[idx1] + d[idx1];
        if(dis2 > mid)
        	can = false;
        
        vector< pair<long long,long long> > v1,v2;
        for(int i=idx5;i<=idx3;i++)
        	v1.push_back(make_pair(sum[i] - sum[idx5] + d[i],sum[idx3] - sum[i] + d[i]));
        for(int i=idx4;i<=idx6;i++)
        	v2.push_back(make_pair(sum[idx6] - sum[i] + d[i],sum[i] - sum[idx4] + d[i]));
        sort(v1.begin(),v1.end());
        sort(v2.begin(),v2.end());
        long long best = -1e18 ;
        int j = 0 ;
        for(int i=v2.size()-1;i>=0;i--){
        	while(j < (int)v1.size() && v1[j].first+v2[i].first+c <= mid){
        		if(v1[j].second+best + sum[idx4] - sum[idx3] > mid)
        			can = false;
        		j++;
        	}
        	best = max(best,v2[i].second);
        }
        while(j <(int)v1.size()){
        	if(v1[j].second+best + sum[idx4] - sum[idx3] > mid)
        			can = false;
        	j++;
        }
        if(can){
            ans = mid;
            right = mid - 1;
        }
        else
            left = mid + 1;
    }
    return ans;

}

• Subtask 1: 9 / 9
• Subtask 2: 14 / 14
• Subtask 3: 8 / 8
• Subtask 4: 7 / 7
• Subtask 5: 33 / 33
• Subtask 6: 22 / 22
• Subtask 7: 4 / 4
• Subtask 8: 0 / 3