freeCodeCamp/curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-96-su-doku.md

---
id: 5900f3cc1000cf542c50fedf
title: 'Problem 96: Su Doku'
challengeType: 5
forumTopicId: 302213
dashedName: problem-96-su-doku
---

# --description--

Su Doku (Japanese meaning *number place*) is the name given to a popular puzzle concept. Its origin is unclear, but credit must be attributed to Leonhard Euler who invented a similar, and much more difficult, puzzle idea called Latin Squares. The objective of Su Doku puzzles, however, is to replace the blanks (or zeros) in a 9 by 9 grid in such that each row, column, and 3 by 3 box contains each of the digits 1 to 9. Below is an example of a typical starting puzzle grid and its solution grid.

<div style="margin: auto; background-color: white; padding: 10px; width: 80%; text-align: center;">
  <table border="0" cellpadding="0" cellspacing="0" align="center">
    <tbody>
      <tr>
        <td>
          <table cellpadding="5" cellspacing="0" border="1">
            <tbody>
              <tr>
                <td style="font-family:'courier new';font-size:14pt; color: black; padding: 5px; border: 2px solid black;">
                  0 0 3<br />9 0 0<br />0 0 1
                </td>
                <td style="font-family:'courier new';font-size:14pt; color: black; padding: 5px; border: 2px solid black;">
                  0 2 0<br />3 0 5<br />8 0 6
                </td>
                <td style="font-family:'courier new';font-size:14pt; color: black; padding: 5px; border: 2px solid black;">
                  6 0 0<br />0 0 1<br />4 0 0
                </td>
              </tr>
              <tr>
                <td style="font-family:'courier new';font-size:14pt; color: black; padding: 5px; border: 2px solid black;">
                  0 0 8<br />7 0 0<br />0 0 6
                </td>
                <td style="font-family:'courier new';font-size:14pt; color: black; padding: 5px; border: 2px solid black;">
                  1 0 2<br />0 0 0<br />7 0 8
                </td>
                <td style="font-family:'courier new';font-size:14pt; color: black; padding: 5px; border: 2px solid black;">
                  9 0 0<br />0 0 8<br />2 0 0
                </td>
              </tr>
              <tr>
                <td style="font-family:'courier new';font-size:14pt; color: black; padding: 5px; border: 2px solid black;">
                  0 0 2<br />8 0 0<br />0 0 5
                </td>
                <td style="font-family:'courier new';font-size:14pt; color: black; padding: 5px; border: 2px solid black;">
                  6 0 9<br />2 0 3<br />0 1 0
                </td>
                <td style="font-family:'courier new';font-size:14pt; color: black; padding: 5px; border: 2px solid black;">
                  5 0 0<br />0 0 9<br />3 0 0
                </td>
              </tr>
            </tbody>
          </table>
        </td>
        <td width="50">
          <img src="images/spacer.gif" width="50" height="1" alt="" /><br />
        </td>
        <td>
          <table cellpadding="5" cellspacing="0" border="1">
            <tbody>
              <tr>
                <td style="font-family:'courier new';font-size:14pt; color: black; padding: 5px; border: 2px solid black;">
                  4 8 3<br />9 6 7<br />2 5 1
                </td>
                <td style="font-family:'courier new';font-size:14pt; color: black; padding: 5px; border: 2px solid black;">
                  9 2 1<br />3 4 5<br />8 7 6
                </td>
                <td style="font-family:'courier new';font-size:14pt; color: black; padding: 5px; border: 2px solid black;">
                  6 5 7<br />8 2 1<br />4 9 3
                </td>
              </tr>
              <tr>
                <td style="font-family:'courier new';font-size:14pt; color: black; padding: 5px; border: 2px solid black;">
                  5 4 8<br />7 2 9<br />1 3 6
                </td>
                <td style="font-family:'courier new';font-size:14pt; color: black; padding: 5px; border: 2px solid black;">
                  1 3 2<br />5 6 4<br />7 9 8
                </td>
                <td style="font-family:'courier new';font-size:14pt; color: black; padding: 5px; border: 2px solid black;">
                  9 7 6<br />1 3 8<br />2 4 5
                </td>
              </tr>
              <tr>
                <td style="font-family:'courier new';font-size:14pt; color: black; padding: 5px; border: 2px solid black;">
                  3 7 2<br />8 1 4<br />6 9 5
                </td>
                <td style="font-family:'courier new';font-size:14pt; color: black; padding: 5px; border: 2px solid black;">
                  6 8 9<br />2 5 3<br />4 1 7
                </td>
                <td style="font-family:'courier new';font-size:14pt; color: black; padding: 5px; border: 2px solid black;">
                  5 1 4<br />7 6 9<br />3 8 2
                </td>
              </tr>
            </tbody>
          </table>
        </td>
      </tr>
    </tbody>
  </table>
</div>

A well constructed Su Doku puzzle has a unique solution and can be solved by logic, although it may be necessary to employ "guess and test" methods in order to eliminate options (there is much contested opinion over this). The complexity of the search determines the difficulty of the puzzle; the example above is considered easy because it can be solved by straight forward direct deduction.

The `puzzlesArr` array contains fifty different Su Doku puzzle strings ranging in difficulty, but all with unique solutions (the first puzzle in the array is the example in the challenge description).

By solving all fifty puzzles find the sum of the 3-digit numbers found in the top left corner of each solution grid; for example, 483 is the 3-digit number found in the top left corner of the solution grid above.

# --hints--

`suDoku(testPuzzles)` should return a number.

```js
assert(typeof suDoku(testPuzzles) === 'number');
```

`suDoku(testPuzzles)` should return 1190.

```js
assert.strictEqual(suDoku(testPuzzles), 1190);
```

`suDoku(puzzlesArr)` should return 24702.

```js
assert.strictEqual(suDoku(puzzlesArr), 24702);
```

# --seed--

## --seed-contents--

```js
function suDoku(arr) {

  return true;
}

// Only change code above this line

const testPuzzles = [
  '003020600900305001001806400008102900700000008006708200002609500800203009005010300',
  '200080300060070084030500209000105408000000000402706000301007040720040060004010003',
  '000000907000420180000705026100904000050000040000507009920108000034059000507000000'
];

const puzzlesArr = [
  '003020600900305001001806400008102900700000008006708200002609500800203009005010300',
  '200080300060070084030500209000105408000000000402706000301007040720040060004010003',
  '000000907000420180000705026100904000050000040000507009920108000034059000507000000',
  '030050040008010500460000012070502080000603000040109030250000098001020600080060020',
  '020810740700003100090002805009040087400208003160030200302700060005600008076051090',
  '100920000524010000000000070050008102000000000402700090060000000000030945000071006',
  '043080250600000000000001094900004070000608000010200003820500000000000005034090710',
  '480006902002008001900370060840010200003704100001060049020085007700900600609200018',
  '000900002050123400030000160908000000070000090000000205091000050007439020400007000',
  '001900003900700160030005007050000009004302600200000070600100030042007006500006800',
  '000125400008400000420800000030000095060902010510000060000003049000007200001298000',
  '062340750100005600570000040000094800400000006005830000030000091006400007059083260',
  '300000000005009000200504000020000700160000058704310600000890100000067080000005437',
  '630000000000500008005674000000020000003401020000000345000007004080300902947100080',
  '000020040008035000000070602031046970200000000000501203049000730000000010800004000',
  '361025900080960010400000057008000471000603000259000800740000005020018060005470329',
  '050807020600010090702540006070020301504000908103080070900076205060090003080103040',
  '080005000000003457000070809060400903007010500408007020901020000842300000000100080',
  '003502900000040000106000305900251008070408030800763001308000104000020000005104800',
  '000000000009805100051907420290401065000000000140508093026709580005103600000000000',
  '020030090000907000900208005004806500607000208003102900800605007000309000030020050',
  '005000006070009020000500107804150000000803000000092805907006000030400010200000600',
  '040000050001943600009000300600050002103000506800020007005000200002436700030000040',
  '004000000000030002390700080400009001209801307600200008010008053900040000000000800',
  '360020089000361000000000000803000602400603007607000108000000000000418000970030014',
  '500400060009000800640020000000001008208000501700500000000090084003000600060003002',
  '007256400400000005010030060000508000008060200000107000030070090200000004006312700',
  '000000000079050180800000007007306800450708096003502700700000005016030420000000000',
  '030000080009000500007509200700105008020090030900402001004207100002000800070000090',
  '200170603050000100000006079000040700000801000009050000310400000005000060906037002',
  '000000080800701040040020030374000900000030000005000321010060050050802006080000000',
  '000000085000210009960080100500800016000000000890006007009070052300054000480000000',
  '608070502050608070002000300500090006040302050800050003005000200010704090409060701',
  '050010040107000602000905000208030501040070020901080406000401000304000709020060010',
  '053000790009753400100000002090080010000907000080030070500000003007641200061000940',
  '006080300049070250000405000600317004007000800100826009000702000075040190003090600',
  '005080700700204005320000084060105040008000500070803010450000091600508007003010600',
  '000900800128006400070800060800430007500000009600079008090004010003600284001007000',
  '000080000270000054095000810009806400020403060006905100017000620460000038000090000',
  '000602000400050001085010620038206710000000000019407350026040530900020007000809000',
  '000900002050123400030000160908000000070000090000000205091000050007439020400007000',
  '380000000000400785009020300060090000800302009000040070001070500495006000000000092',
  '000158000002060800030000040027030510000000000046080790050000080004070100000325000',
  '010500200900001000002008030500030007008000500600080004040100700000700006003004050',
  '080000040000469000400000007005904600070608030008502100900000005000781000060000010',
  '904200007010000000000706500000800090020904060040002000001607000000000030300005702',
  '000700800006000031040002000024070000010030080000060290000800070860000500002006000',
  '001007090590080001030000080000005800050060020004100000080000030100020079020700400',
  '000003017015009008060000000100007000009000200000500004000000020500600340340200000',
  '300200000000107000706030500070009080900020004010800050009040301000702000000008006'
];

suDoku(testPuzzles);
```

# --solutions--

```js
// solution required
```