solve 15

1 files changed, 54 insertions, 0 deletions

diff --git a/0015/main.pas b/0015/main.pas
new file mode 100644
index 0000000..2bb5ba1
--- /dev/null
+++ b/0015/main.pas
@@ -0,0 +1,54 @@
+program main;
+
+type
+    Row = Array[0..20] of Int64;
+    Grid = Array[0..20] of Row;
+
+var
+    gridpath: Grid;
+
+procedure init_grid();
+var
+    i, j: Integer;
+begin
+    for i := 0 to 20 do
+    begin
+        for j := 0 to 20 do
+            gridpath[i][j] := -1;
+    end;
+end;
+
+procedure calc(row: Integer; col: Integer);
+var
+    r, c: Integer;
+    ret: Int64;
+begin
+    ret := 0;
+    if gridpath[row][col] <> -1 then
+        exit;
+
+    r := row + 1;
+    c := col;
+    if (r <= 20) and (c <= 20) then
+    begin
+        calc(r, c);
+        ret := ret + gridpath[r][c];
+    end;
+
+    r := row;
+    c := col + 1;
+    if (r <= 20) and (c <= 20) then
+    begin
+        calc(r, c);
+        ret := ret + gridpath[r][c];
+    end;
+    gridpath[row][col] := ret;
+end;
+
+begin
+    init_grid();
+    gridpath[20][20] := 1;
+    calc(0, 0);
+    writeLn(gridpath[0][0]);
+end.
+