2010-11-17 12:00:00 UTC

# Some say that he really is the missing link between Tennis and Formula 1

by Magnus S

Status: Passed
Results: 4022 (cyc: 10, node: 2436)
CPU Time: 64.88
Score: 810.48
Submitted at: 2010-11-17 15:21:06 UTC
Scored at: 2010-11-17 15:29:46 UTC

Code
```function [thrustRow, thrustCol] = solver(chart, aIndex, bIndex, maxThrottle)

[thrustRow, thrustCol] = nickelfelpeterv3(chart, aIndex, bIndex, maxThrottle);
score1 = runsolution(thrustRow, thrustCol, chart(:,:,2), chart(:,:,1), aIndex, bIndex);
if score1<18
return
end

[thrustRow0, thrustCol0, score0] = nickelfelpeterv2(chart, aIndex, bIndex, maxThrottle);

if score0<score1,
thrustRow=thrustRow0;
thrustCol=thrustCol0;
end

end

function [thrustRow, thrustCol, score] = nickelfelpeterv2(chart, aIndex, bIndex, maxThrottle)
%REP
%by Gwendolyn Fischer
%r4537 t44

ONEHUNDRED = 100;

y_winds         = chart(:,:,1);
x_winds         = chart(:,:,2);
[ny,nx]         = size(x_winds);
ay              = rem(aIndex-1, ny) + 1;
ax              = (aIndex - ay)/ny  + 1;
by              = rem(bIndex-1, ny) + 1;
bx              = (bIndex - by)/ny  + 1;
x               = (1:nx);
y               = (1:ny)';
X               = x(ones(ny,1),:);
Y               = y(:,ones(nx,1));
dist_to_B       = (X - bx).^2 + (Y - by).^2;
dist_to_A       = (X - ax).^2 + (Y - ay).^2;

maxIter         = 1034;
SDBiter         = [200 200];
INF             = 100000;
SDBzoom         = [INF 1/2];

dist_to_B_w     = dist_to_B*1e-4;
dist_to_A_w     = dist_to_A*1e-4;

y_dir           = 2*(by > ay) - 1;
x_dir           = 2*(bx > ax) - 1;
fuel            = Inf(ny,nx);
fuel(aIndex)    = 0;
fuel_to_reverse = fuel;
xvel            = zeros(ny,nx);
yvel            = zeros(ny,nx);
checked         = zeros(ny,nx);
previous_stop   = zeros(ny,nx);
min_fuel        = 0;
[cost_to_B cost_to_B_idx] = min(fuel_to_reverse(:) + dist_to_B(:));
zoon = nx*ny*SDBzoom.^2;

for i = 1:2

SDB_tf = dist_to_B(:)<=zoon(i);
SDB_idx = find(SDB_tf);

SDBchecked = checked(SDB_tf);
SDBfuel = fuel(SDB_tf);
SDBfuel_to_reverse = fuel_to_reverse(SDB_tf);
SDBdist_to_B_w = dist_to_B_w(SDB_tf);
SDBdist_to_B = dist_to_B(SDB_tf);
SDBxvel = xvel(SDB_tf);
SDByvel = yvel(SDB_tf);
SDBX = X(SDB_tf);
SDBY = Y(SDB_tf);
SDBprevious_stop = previous_stop(SDB_tf);
SDBcost_to_B_idx = find(cost_to_B_idx==SDB_idx);

it = 0;
slowDown = maxThrottle+SDBdist_to_B/4-4;
while (  min_fuel <= cost_to_B  && ~all(SDBchecked) && it < SDBiter(i))
it                      = it + 1;
metrix                  = SDBfuel + SDBchecked + SDBdist_to_B_w;
[dummy,i_p]              = min(metrix(:));
i_p_full                = SDB_idx(i_p);
min_fuel                = SDBfuel(i_p);
i_y                     = rem(i_p_full - 1,ny) + 1;
i_x                     = (i_p_full - i_y)/ny  + 1;
i_vy                    = SDByvel(i_p) + y_winds(i_p_full);
i_vx                    = SDBxvel(i_p) + x_winds(i_p_full);
i_new_vy                = SDBY - i_y;
i_new_vx                = SDBX - i_x;
i_thrust                = abs(i_new_vx - i_vx) + abs(i_new_vy - i_vy);
i_fuel                  = i_thrust + min_fuel;
i_reacheable            = (i_thrust <= maxThrottle) & (abs(i_new_vy+y_winds(i_p_full))+abs(i_new_vx+x_winds(i_p_full))<slowDown);
i_optimum               = i_fuel < SDBfuel;
i_impr_tf               = i_reacheable & i_optimum;
i_impr_idx              = find(i_impr_tf);
if isempty(i_impr_idx)
SDBchecked(i_p)            = ONEHUNDRED; %true;
continue;
end
i_fuel_impr             = i_fuel  (i_impr_idx) ;
SDBxvel           (i_impr_idx) = i_new_vx(i_impr_idx);
SDByvel           (i_impr_idx) = i_new_vy(i_impr_idx);
SDBfuel           (i_impr_idx) = i_fuel_impr;
SDBprevious_stop  (i_impr_idx) = i_p_full;
cost_to_B = min(cost_to_B,min(SDBfuel(i_impr_idx) + SDBdist_to_B(i_impr_idx)));
SDBchecked(i_impr_idx)     = 0; %false;
SDBchecked(i_p)            = ONEHUNDRED; %true;
end

fuel(SDB_tf) = SDBfuel;
previous_stop(SDB_tf) = SDBprevious_stop;
xvel(SDB_tf) = SDBxvel;
yvel(SDB_tf) = SDByvel;

end

fuel                    = fuel + dist_to_B;
[cost_to_A cost_to_A_idx] = min(fuel(:) + dist_to_A(:));

checked                 = checked*0;
return_previous_stop    = zeros(ny,nx);

it                      = 0;
min_fuel                = 0;

while ( min_fuel < cost_to_A &&  ~all(checked(:)) && it < maxIter )

it                  = it + 1;
metrix              = fuel + checked + dist_to_A_w; %****
[dummy,i_p]             = min(metrix(:)); %****
min_fuel            = fuel(i_p); %****

i_y                 = rem(i_p - 1,ny) + 1;
i_x                 = (i_p - i_y)/ny  + 1;
i_vy                = yvel(i_p) + y_winds(i_p);
i_vx                = xvel(i_p) + x_winds(i_p);
i_new_vy            = Y-i_y;
i_new_vx            = X-i_x;
i_thrust            = abs(i_new_vx - i_vx) + abs(i_new_vy - i_vy);
i_fuel              = i_thrust + min_fuel;
i_reacheable        = i_thrust <= maxThrottle;
i_optimum           = i_fuel < fuel;
i_impr_tf           = i_reacheable & i_optimum;
i_impr_idx          = find(i_impr_tf);
if isempty(i_impr_idx)
checked(i_p)            = ONEHUNDRED; %true;
continue;
end
fuel                (i_impr_idx) = i_fuel(i_impr_idx);
xvel                (i_impr_idx) = i_new_vx(i_impr_idx);
yvel                (i_impr_idx) = i_new_vy(i_impr_idx);
return_previous_stop(i_impr_idx) = i_p;
cost_to_A = min(cost_to_A,min(fuel(i_impr_idx) + dist_to_A(i_impr_idx)));
%checked(i_impr_idx) = 0;
checked(i_p)        = 100;
checked(i_impr_idx) = 0;
end

cost_to_A           = fuel + dist_to_A;
[dummy,min_fuel]        = min(cost_to_A(:));
indices             = zeros(nx*ny,1);
indices(1)          = min_fuel(1);
next_move           = return_previous_stop(indices(1));
k                   = 1;
[indices, k] = while_next_move(indices, k, next_move, return_previous_stop);
next_move           = previous_stop(indices(k));
[indices, k] = while_next_move(indices, k, next_move, previous_stop);
indices             = indices(k:-1:1);

ypos                = rem(indices - 1, ny) + 1;
xpos                = (indices - ypos)/ny + 1;
xw                  = x_winds(indices);
yw                  = y_winds(indices);

xspeed              = diff(xpos);
yspeed              = diff(ypos);

xdrive              = diff([0; xspeed]);
ydrive              = diff([0; yspeed]);

thrustCol           = xdrive - xw(1:end-1);
thrustRow           = ydrive - yw(1:end-1);

score = min((xpos-bx).^2 + (ypos-by).^2) + sum(abs(thrustCol))+sum(abs(thrustRow)) + (ypos(end)-ay).^2 + (xpos(end)-ax).^2;
end

function [thrustRow, thrustCol] = nickelfelpeterv3(chart, aIndex, bIndex, maxThrottle)
%continue
%by Sebastian Ullmann
%r4107 t50

y_winds         = chart(:,:,1);
x_winds         = chart(:,:,2);
[ny,nx]         = size(x_winds);
ay              = rem(aIndex-1, ny) + 1;
ax              = (aIndex - ay)/ny  + 1;
by              = rem(bIndex-1, ny) + 1;
bx              = (bIndex - by)/ny  + 1;
x               = (1:nx);
y               = (1:ny)';
X               = x(ones(ny,1),:);
Y               = y(:,ones(nx,1));

dist_to_B       = ((X - bx).^2 + (Y - by).^2).^1.15;
dist_to_A       = ((X - ax).^2 + (Y - ay).^2).^1.155;

dist_to_B_w     = dist_to_B*1e-4;
dist_to_A_w     = dist_to_A*1e-4;

fuel            = 100*ones(ny,nx);
fuel(aIndex)    = 0;
xvel            = zeros(ny,nx);
yvel            = xvel;
checked         = xvel;
previous_stop   = xvel;
min_fuel        = 0;
cost_to_B = dist_to_B(aIndex);
zoon = nx*ny*[10 0.37];
ziter = [500 700];% .* mxrand(-0.05);
sf = [0.31 0.19];

for i = 1:2

SDB_tf = dist_to_B(:)<=zoon(i);
SDB_idx = find(SDB_tf);

SDBchecked = checked(SDB_tf);
SDBfuel = fuel(SDB_tf);
SDBdist_to_B_w = dist_to_B_w(SDB_tf);
SDBdist_to_B = dist_to_B(SDB_tf);
SDBxvel = xvel(SDB_tf);
SDByvel = yvel(SDB_tf);
SDBX = X(SDB_tf);
SDBY = Y(SDB_tf);
SDBprevious_stop = previous_stop(SDB_tf);

slowdown = maxThrottle+SDBdist_to_B*sf(i);

it = 0;

while (  min_fuel < cost_to_B  && ~all(SDBchecked) && it < ziter(i))
it                      = it + 1;
metrix                  = SDBfuel + SDBchecked + SDBdist_to_B_w;
[dummy,i_p]             = min(metrix);
i_p_full                = SDB_idx(i_p);
min_fuel                = SDBfuel(i_p);
i_y                     = rem(i_p_full - 1,ny) + 1;
i_x                     = (i_p_full - i_y)/ny  + 1;
i_y_winds               = y_winds(i_p_full);
i_x_winds               = x_winds(i_p_full);
i_vy                    = SDByvel(i_p) + i_y_winds;
i_vx                    = SDBxvel(i_p) + i_x_winds;
i_new_vy                = SDBY - i_y;
i_new_vx                = SDBX - i_x;
i_thrust                = abs(i_new_vx - i_vx) + abs(i_new_vy - i_vy);
i_fuel                  = i_thrust + min_fuel;
i_impr_tf               = (i_thrust <= maxThrottle) & (abs(i_new_vy+i_y_winds)+abs(i_new_vx+i_x_winds)<slowdown) & (i_fuel < SDBfuel);
i_impr_idx              = find(i_impr_tf);
if isempty(i_impr_idx)
SDBchecked(i_p)            = 100; %true;
continue;
end
i_fuel_impr             = i_fuel  (i_impr_idx) ;
SDBxvel           (i_impr_idx) = i_new_vx(i_impr_idx);
SDByvel           (i_impr_idx) = i_new_vy(i_impr_idx);
SDBfuel           (i_impr_idx) = i_fuel_impr;
SDBprevious_stop  (i_impr_idx) = i_p_full;
cost_to_B = min(cost_to_B,min(SDBfuel(i_impr_idx) + SDBdist_to_B(i_impr_idx)));
%SDBchecked(i_impr_idx)     = 0; %false;
SDBchecked(i_p)            = 100; %true;
SDBchecked(i_impr_idx)     = 0; %false;
end

fuel(SDB_tf) = SDBfuel;
previous_stop(SDB_tf) = SDBprevious_stop;
xvel(SDB_tf) = SDBxvel;
yvel(SDB_tf) = SDByvel;

end

fuel                    = fuel + dist_to_B;
cost_to_A               = min(fuel(:) + dist_to_A(:));

checked(:)                 = 0;
return_previous_stop    = checked;

it                      = 0;
min_fuel                = 0;

while ( min_fuel < cost_to_A &&  ~all(checked(:)) && it < min(nx*ny,2000))

it                  = it + 1;
metrix              = fuel + checked + dist_to_A_w; %****
[dummy,i_p]             = min(metrix(:)); %****
min_fuel            = fuel(i_p); %****

i_y                 = rem(i_p - 1,ny) + 1;
i_x                 = (i_p - i_y)/ny  + 1;
i_vy                = yvel(i_p) + y_winds(i_p);
i_vx                = xvel(i_p) + x_winds(i_p);
i_new_vy            = Y-i_y;
i_new_vx            = X-i_x;
i_thrust            = abs(i_new_vx - i_vx) + abs(i_new_vy - i_vy);
i_fuel              = i_thrust + min_fuel;
i_impr_tf           = i_thrust <= maxThrottle & i_fuel < fuel;
i_impr_idx          = find(i_impr_tf);
if isempty(i_impr_idx)
checked(i_p)            = 100; %true;
continue;
end
fuel                (i_impr_idx) = i_fuel(i_impr_idx);
xvel                (i_impr_idx) = i_new_vx(i_impr_idx);
yvel                (i_impr_idx) = i_new_vy(i_impr_idx);
return_previous_stop(i_impr_idx) = i_p;
cost_to_A = min(cost_to_A,min(fuel(i_impr_idx) + dist_to_A(i_impr_idx)));
checked(i_impr_idx) = 0;
checked(i_p)        = 100;

end

cost_to_A           = fuel + dist_to_A;
[dummy,min_fuel]        = min(cost_to_A(:));
indices             = zeros(nx*ny,1);
indices(1)          = min_fuel(1);
next_move           = return_previous_stop(indices(1));
k                   = 1;
[indices, k] = while_next_move(indices, k, next_move, return_previous_stop);
next_move           = previous_stop(indices(k));
[indices, k] = while_next_move(indices, k, next_move, previous_stop);
indices             = indices(k:-1:1);

ypos                = rem(indices - 1, ny) + 1;
xpos                = (indices - ypos)/ny + 1;
xw                  = x_winds(indices);
yw                  = y_winds(indices);

thrustCol           = diff([0; diff(xpos)]) - xw(1:end-1);
thrustRow           = diff([0; diff(ypos)]) - yw(1:end-1);

end

function [indices, k] = while_next_move(indices, k, next_move, previous_stop)

while(next_move)
k               = k + 1;
indices(k)      = next_move;
next_move       = previous_stop(next_move);
end

end

function score = runsolution(thrustRow, thrustCol, colWind, rowWind, aIndex, bIndex)
% RUNSOLUTION Simulates the navigation trajectory given the winds and the
% motor thrust.

[ny,nx]         = size(colWind);

AR              = rem(aIndex-1, ny) + 1;
AC              = (aIndex - AR)/ny  + 1;
BR              = rem(bIndex-1, ny) + 1;
BC              = (bIndex - BR)/ny  + 1;

% Initialize variables at start point (A)
fR = AR; fC =AC;
fvR = 0; fvC = 0;
dB = (fR-BR)^2 + (fC-BC)^2;

for i = 1:numel(thrustRow)
ivR = fvR + thrustRow(i) + rowWind(fR,fC);
ivC = fvC + thrustCol(i) + colWind(fR,fC);
fR = fR + ivR;
fC = fC + ivC;
fvR = ivR;
fvC = ivC;
% Verify if this is the closest point to B
dBtmp = (fR-BR)^2 + (fC-BC)^2;
if  dBtmp < dB
dB = dBtmp;
end
end
dA = (fR-AR)^2 + (fC-AC)^2; % Final distance to A
score = dB + dA + sum(abs(thrustRow)) + sum(abs(thrustCol));
end
```