81 lines
1.4 KiB
ObjectPascal
81 lines
1.4 KiB
ObjectPascal
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program main;
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var
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arr: array[0..109] of integer;
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n: integer;
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m, a, b, k, loc, i: integer;
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flag: boolean;
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procedure init(n: integer);
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var i: integer;
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begin
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for i := 1 to n * n + 1 do
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arr[i] := -1;
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end;
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function findfa(a: integer):integer;
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begin
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if arr[a] = a then
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findfa := a
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else
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begin
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arr[a] := findfa(arr[a]);
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findfa := arr[a];
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end;
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end;
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procedure mmerge(a, b: integer);
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var m, n: integer;
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begin
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m := findfa(a);
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n := findfa(b);
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if m <> n then
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arr[m] := n;
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end;
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begin
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n := 4;
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m := 10;
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flag := false;
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init(n);
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k := n * n + 1;
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for i := 0 to m - 1 do
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begin
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read(a);
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read(b);
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if flag = false then
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begin
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loc := n * (a - 1) + b;
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arr[loc] := loc;
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if a = 1 then
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begin
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arr[0] := 0;
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mmerge(loc, 0);
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end;
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if a = n then
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begin
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arr[k] := k;
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mmerge(loc, k);
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end;
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if (b < n) and (arr[loc + 1] <> -1) then
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mmerge(loc, loc + 1);
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if (b > 1) and (arr[loc - 1] <> -1) then
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mmerge(loc, loc - 1);
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if (a < n) and (arr[loc + n] <> -1) then
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mmerge(loc, loc + n);
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if (a > 1) and (arr[loc - n] <> -1) then
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mmerge(loc, loc - n);
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if (arr[0] <> -1) and (arr[k] <> -1) and (findfa(0) = findfa(k)) then
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begin
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flag := true;
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write(i + 1);
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end;
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end;
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end;
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if flag = false then
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write(-1);
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end.
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