Submission #71542

#	Time	Username	Problem	Language	Result	Execution time	Memory
71542		top34051	Shortcut (IOI16_shortcut)	C++17	71 / 100	808 ms	4488 KiB

shortcut

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

#define ll long long
const int maxn = 3000 + 5;
const ll inf = 1e15;

int n;
ll cost, len[maxn], val[maxn];
ll pos[maxn];

bool check(ll k) {
//    printf("check %lld\n",k);
    double r1 = -inf, r2 = inf, c1 = -inf, c2 = inf;
    for(int x=0;x<n;x++) {
        for(int y=x+1;y<n;y++) {
            if(val[x] + val[y] + pos[y] - pos[x] <= k) continue;
            ll d = k - cost - val[x] - val[y];
//            double r1 = (pos[x] + pos[y] - d)/(2.0*sqrt(2)), c1 = (-pos[x] + pos[y] - d)/(2.0*sqrt(2));
//            double r2 = (pos[x] + pos[y] + d)/(2.0*sqrt(2)), c2 = (-pos[x] + pos[y] + d)/(2.0*sqrt(2));
//            printf("%d %d: (%.3lf, %.3lf) (%.3lf, %.3lf)\n",x,y,r1,c1,r2,c2);
            r1 = max(r1, (pos[x] + pos[y] - d)/(2.0*sqrt(2)));
            c1 = max(c1, (-pos[x] + pos[y] - d)/(2.0*sqrt(2)));
            r2 = min(r2, (pos[x] + pos[y] + d)/(2.0*sqrt(2)));
            c2 = min(c2, (-pos[x] + pos[y] + d)/(2.0*sqrt(2)));
        }
    }
    for(int x=0;x<n;x++) {
        for(int y=x+1;y<n;y++) {
//            printf("\tuse (%.3lf, %.3lf)\n",(pos[x]+pos[y])/(2.0*sqrt(2)),(-pos[x]+pos[y])/(2.0*sqrt(2)));
            double r = (pos[x]+pos[y])/(2.0*sqrt(2)), c = (-pos[x]+pos[y])/(2.0*sqrt(2));
            if(r1 <= r && r<= r2 && c1 <= c && c<= c2) return 1;
        }
    }
    return 0;
}

ll solve() {
    for(int i=0;i<n-1;i++) pos[i+1] = pos[i] + len[i];
    ll l = 0, r = inf, mid, res = -1;
    while(l<=r) {
        mid = (l+r)/2;
        if(check(mid)) {
            res = mid;
            r = mid-1;
        }
        else l = mid+1;
    }
    return res;
}

ll find_shortcut(int N, vector<int> l, vector<int> d, int c) {
    n = N; cost = c;
    for(int i=0;i<n-1;i++) len[i] = l[i];
    for(int i=0;i<n;i++) val[i] = d[i];
    return solve();
}

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