Given a 2D matrix of booleans representing a block of land/water
False means that slot has land
True means that slot has water

Assign a height to each tile such that:
Water is at level 0
Two adjacent tiles heights differences must be at most 1

Find the highest tile (just its height, don’t care about which time)





T 1 7 F F F
3 2 8 F F F
11 10 9 F F F
F F F 13 5 6
F F F 12 4 T

T 1 F F
1 1 1 1
F F 1 T
F F F T

0 1 2 ?
1 1 2 2
? ? 1 1
? ? 1 0

0 1 2 ?
1 1 2 ?
2 2 2? ?
? ? ? 0

0 1 1 T 1 F
1 1 1 1 1 1
F 1 1 1 T 1
F 1 T 1 1 1
T 1 1 1 1 0



Class pair {
Int x;
Int y;
}

bool[][] matrix = ...;
Int heights[][] = new int[matrix.length][matrix[0].length]:

Queue<Pair> nextOnesToLookAt;
Loop through matrix
Pair[] waters = …Pair[1][1]
nextOneToLookAt.addAll(waters);

While (queue not empty) {
  Pair p = queue.next()
  Pair[] adjacents = GetAdjacents(p)
  queue.addAll(adjacents)
  For (Pair a : adjacent) {
    Pair[] doubleAdjacents = GetAdjacents(a);
    Int LowestHeight = Lowest(doubleAdjacents);
  Heights[a.x][a.y] = LowestHeight + 1;
  }
}

// loop through heights find max
Return max

Breadth first search



/** Also includes diagonals */
Pair[] GetAdjacent(Pair p, int maxlen, int maxwidth)
  … +1 -1 all that bs
  .. dont go below zero
  .. dont go above or equal to the maxes
  .. dont visit existing visited nodes  == either water by checking boolean, or height nonzero

/** Find the lowest height out of this list */
Int Lowest(Pair[] ps) {
  Int[] t= new int[ps.length];
  For (int i = 0; i < ps.length; i++) t[i] =  heights[p.x][p.y]
  Return Arrays.min(t);
}Given a 2D matrix of booleans representing a block of land/water
False means that slot has land
True means that slot has water

Assign a height to each tile such that:
Water is at level 0
Two adjacent tiles heights differences must be at most 1

Find the highest tile (just its height, don’t care about which time)





T 1 7 F F F
3 2 8 F F F
11 10 9 F F F
F F F 13 5 6
F F F 12 4 T

T 1 F F
1 1 1 1
F F 1 T
F F F T

0 1 2 ?
1 1 2 2
? ? 1 1
? ? 1 0

0 1 2 ?
1 1 2 ?
2 2 2? ?
? ? ? 0

0 1 1 T 1 F
1 1 1 1 1 1
F 1 1 1 T 1
F 1 T 1 1 1
T 1 1 1 1 0



Class pair {
Int x;
Int y;
}

bool[][] matrix = ...;
Int heights[][] = new int[matrix.length][matrix[0].length]:

Queue<Pair> nextOnesToLookAt;
Loop through matrix
Pair[] waters = …Pair[1][1]
nextOneToLookAt.addAll(waters);

While (queue not empty) {
  Pair p = queue.next()
  Pair[] adjacents = GetAdjacents(p)
  queue.addAll(adjacents)
  For (Pair a : adjacent) {
    Pair[] doubleAdjacents = GetAdjacents(a);
    Int LowestHeight = Lowest(doubleAdjacents);
  Heights[a.x][a.y] = LowestHeight + 1;
  }
}

// loop through heights find max
Return max

Breadth first search



/** Also includes diagonals */
Pair[] GetAdjacent(Pair p, int maxlen, int maxwidth)
  … +1 -1 all that bs
  .. dont go below zero
  .. dont go above or equal to the maxes
  .. dont visit existing visited nodes  == either water by checking boolean, or height nonzero

/** Find the lowest height out of this list */
Int Lowest(Pair[] ps) {
  Int[] t= new int[ps.length];
  For (int i = 0; i < ps.length; i++) t[i] =  heights[p.x][p.y]
  Return Arrays.min(t);
}