Submission #4234955

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Source Code Expand

import std.stdio, std.array, std.string, std.conv, std.algorithm;
import std.typecons, std.range, std.random, std.math, std.container;
import std.numeric, std.bigint, core.bitop, core.stdc.string, std.datetime;

alias Point = Tuple!(long, "x", long, "y");

immutable int N = 200;

long dist2(Point p1, Point p2) {
    return (p1.x - p2.x) ^^ 2 + (p1.y - p2.y) ^^ 2;
}

void main() {
    auto stattime = Clock.currTime();

    readln;
    auto P = new Point[](N);
    foreach (i; 0..N) {
        auto s = readln.split.map!(to!long);
        P[i] = tuple(s[0], s[1]);
    }

    auto D = new long[][](N, N);
    long[] X;

    foreach (i; 0..N) {
        foreach (j; i+1..N) {
            D[i][j] = D[j][i] = dist2(P[i], P[j]);
            X ~= D[i][j];
        }
    }

    X.sort();
    long M = X[X.length/2];


    real calc_score(const ref int[] p) {
        real v = 0;
        real s = 0;
        foreach (i; 0..N) {
            int j = (i + 1) % N;
            s += D[p[i]][p[j]];
        }
        s /= N;
        foreach (i; 0..N) {
            int j = (i + 1) % N;
            v += (D[p[i]][p[j]] - s) ^^ 2;
        }
        return v;
    }


    auto used = new bool[](N);
    real best_score = 1L << 59;
    int[] best_ans;

    foreach (cur; 0..N) {
        used[] = false;
        int[] ans = [cur];
        foreach (i; 0..N-1) {
            long mind = 1L << 59;
            int mini = -1;
            used[cur] = true;
            foreach (j; 0..N) {
                if (used[j] || j == cur) continue;
                long diff = abs(M - D[cur][j]);
                if (diff < mind) {
                    mind = diff;
                    mini = j;
                }
            }
            ans ~= mini;
            cur = mini;
        }
        real s = calc_score(ans);
        if (s < best_score) {
            best_score = s;
            best_ans = ans.dup;
        }
    }

    while ((Clock.currTime - stattime).total!"msecs" < dur!"msecs"(1900).total!"msecs") {
        int x, y;
        do {
            x = uniform(0, N);
            y = uniform(0, N);
        } while (x == y);

        real old_score = best_score;
        swap(best_ans[x], best_ans[y]);
        real new_score = calc_score(best_ans);
        if (new_score > old_score) swap(best_ans[x], best_ans[y]);
        else best_score = new_score;
    }

    best_ans.each!writeln;
}

Submission Info

Judge Result