int trap(int A[], int n) {
if(n<3) return 0;
vector <int > leftmax(n,0);
vector <int > rightmax(n,0);
int left=A[0];
for(int i=1;i<n-1;i++)
{
if(A[i-1]>left)
{
left=A[i-1];
}
leftmax[i]=left;
}
int right=A[n-1];
for(int i=n-2;i>0;i--)
{
if(A[i+1]>right)
{
right=A[i+1];
}
rightmax[i]=right;
}
int res=0;
for(int i=1;i<n-1;i++)
{
int h=min(rightmax[i],leftmax[i]);
if(h-A[i]>0)
res+=h-A[i];
}
return res;
}
void build(int *indices, int numindices, const vec &vmin, const vec &vmax)
{
int axis = 2;
loopk(2) if(vmax[k] - vmin[k] > vmax[axis] - vmin[axis]) axis = k;
vec leftmin(1e16f, 1e16f, 1e16f), leftmax(-1e16f, -1e16f, -1e16f), rightmin(1e16f, 1e16f, 1e16f), rightmax(-1e16f, -1e16f, -1e16f);
float split = 0.5f*(vmax[axis] + vmin[axis]), splitleft = -1e16f, splitright = 1e16f;
int left, right;
for(left = 0, right = numindices; left < right;)
{
waypoint &w = waypoints[indices[left]];
float radius = WAYPOINTRADIUS;
if(max(split - (w.o[axis]-radius), 0.0f) > max((w.o[axis]+radius) - split, 0.0f))
{
++left;
splitleft = max(splitleft, w.o[axis]+radius);
leftmin.min(vec(w.o).sub(radius));
leftmax.max(vec(w.o).add(radius));
}
else
{
--right;
swap(indices[left], indices[right]);
splitright = min(splitright, w.o[axis]-radius);
rightmin.min(vec(w.o).sub(radius));
rightmax.max(vec(w.o).add(radius));
}
}
if(!left || right==numindices)
{
leftmin = rightmin = vec(1e16f, 1e16f, 1e16f);
leftmax = rightmax = vec(-1e16f, -1e16f, -1e16f);
left = right = numindices/2;
splitleft = -1e16f;
splitright = 1e16f;
loopi(numindices)
{
waypoint &w = waypoints[indices[i]];
float radius = WAYPOINTRADIUS;
if(i < left)
{
splitleft = max(splitleft, w.o[axis]+radius);
leftmin.min(vec(w.o).sub(radius));
leftmax.max(vec(w.o).add(radius));
}
else
{
splitright = min(splitright, w.o[axis]-radius);
rightmin.min(vec(w.o).sub(radius));
rightmax.max(vec(w.o).add(radius));
}
}
}
