diff --git a/apps/n-dame-problem/src/n-dame-backtracking.ts b/apps/n-dame-problem/src/n-dame-backtracking.ts
new file mode 100644
index 0000000..afc8146
--- /dev/null
+++ b/apps/n-dame-problem/src/n-dame-backtracking.ts
@@ -0,0 +1,22 @@
+import { NDameModel } from './n-dame-model';
+
+export class NDameBacktracking {
+  private model: NDameModel;
+
+  constructor(private readonly modelSize: number) {
+    this.model = new NDameModel(modelSize);
+  }
+
+  options = (): Array<number> => {
+    // const optionsArray = Array.from(
+    //   { length: this.modelSize },
+    //   (value, index) => index,
+    // );
+    // wir können nur 1 Dame pro Feld platzieren !!!
+    return [1];
+  };
+
+  solved = (): boolean => {
+    return this.model.solved();
+  };
+}
diff --git a/apps/n-dame-problem/src/n-dame-model.ts b/apps/n-dame-problem/src/n-dame-model.ts
new file mode 100644
index 0000000..f3d3073
--- /dev/null
+++ b/apps/n-dame-problem/src/n-dame-model.ts
@@ -0,0 +1,192 @@
+import { IBacktracking } from '@app/backtracking-lib/backtracking.interface';
+import { MatrixPosition } from '@app/backtracking-lib/matrix-position';
+import { Logger } from '@nestjs/common';
+
+enum EDiagonal {
+  NW_SO = 1,
+  NO_SW = -1,
+}
+
+export class NDameModel implements IBacktracking {
+  private readonly logger = new Logger(this.constructor.name);
+
+  private nDamesMatrix: boolean[][] = [];
+  // Wert initial setzen, damit nextPosition beim ersten Schritt richtig platziert wird
+  private modelPosition: MatrixPosition = new MatrixPosition(
+    -1,
+    this.modelSize - 1,
+  );
+
+  constructor(private readonly modelSize: number) {
+    this.initNDameField();
+  }
+
+  private initNDameField() {
+    for (var zeile = 0; zeile < this.modelSize; zeile++) {
+      this.nDamesMatrix[zeile] = [];
+      for (var spalte = 0; spalte < this.modelSize; spalte++) {
+        this.nDamesMatrix[zeile].push(false);
+      }
+    }
+  }
+
+  public get matrix(): boolean[][] {
+    return this.nDamesMatrix;
+  }
+
+  // getter: Anzahl der gesetzten Damen
+  private get dames(): number {
+    const arrOfMatrix = this.nDamesMatrix.flat();
+    const dames = arrOfMatrix.reduce((a, b: boolean) => (b ? a + 1 : a), 0);
+    return dames;
+  }
+
+  // sind alle N Damen auf dem Feld platziert ?
+  public solved = (): boolean => {
+    return this.dames == this.modelSize;
+  };
+
+  options = (): Array<number> => {
+    // wir können nur 1 Dame pro Feld platzieren !!!
+    return [1];
+
+    // const optionsArray = Array.from(
+    //   { length: this.modelSize },
+    //   (value, index) => index,
+    // );
+  };
+
+  nextPosition = () => {
+    this.modelPosition.col++;
+
+    if (this.modelPosition.col == this.modelSize) {
+      this.modelPosition.row++;
+      this.modelPosition.col = 0;
+    }
+
+    if (this.modelPosition.row == this.modelSize)
+      throw new Error(`model bounds crashed...\n${this.modelPosition}`);
+
+    return this.modelPosition;
+  };
+
+  private rowProhibited = (): boolean => {
+    const damesRow = this.nDamesMatrix[this.modelPosition.row];
+
+    // steht schon eine Dame in der selben Zeile ?
+    const damesInRow = damesRow.reduce((acc, act) => (act ? ++acc : acc), 0);
+
+    if (damesInRow > 1)
+      this.logger.error(`row occupied: ${this.modelPosition}`);
+
+    return damesInRow > 1;
+  };
+
+  private colProhibited = (): boolean => {
+    const damesCol = this.nDamesMatrix.reduce((acc, act) => {
+      acc.push(act[this.modelPosition.col]);
+      return acc;
+    }, []);
+
+    // steht schon eine Dame in der selben Spalte ?
+    const damesInCol = damesCol.reduce((acc, act) => (act ? ++acc : acc), 0);
+
+    if (damesInCol > 1)
+      this.logger.error(`col occupied: ${this.modelPosition}`);
+
+    return damesInCol > 1;
+  };
+
+  private damesInDiagonal = (diagDirection: EDiagonal) => {
+    this.logger.log(
+      `diaginal ${diagDirection == EDiagonal.NW_SO ? 'NW_SO' : 'NO_SW'}`,
+    );
+
+    // const startPos = { ...this.modelPosition };
+    const startPos = new MatrixPosition(
+      this.modelPosition.row,
+      this.modelPosition.col,
+    );
+    const colSearchEndPos =
+      diagDirection == EDiagonal.NW_SO ? 0 : this.modelSize - 1;
+
+    var found = false;
+
+    while (!found) {
+      if (startPos.row == 0 || startPos.col == colSearchEndPos) found = true;
+      else {
+        --startPos.row;
+        startPos.col += -diagDirection;
+      }
+    }
+
+    var diagReady = false;
+    var diagPos = startPos;
+    const diagCoords = [];
+    const damesDiag = [];
+    const colExitPos = diagDirection == EDiagonal.NW_SO ? this.modelSize : -1;
+    while (!diagReady) {
+      if (diagPos.row == this.modelSize || diagPos.col == colExitPos)
+        diagReady = true;
+      else {
+        diagCoords.push(new MatrixPosition(diagPos.row, diagPos.col));
+        damesDiag.push(this.nDamesMatrix[diagPos.row][diagPos.col]);
+        ++diagPos.row;
+        diagPos.col += diagDirection;
+      }
+    }
+
+    this.logger.verbose(diagCoords.join());
+    return damesDiag;
+  };
+
+  private diagonalsProhibited = (): boolean => {
+    const diagNW_SO = this.damesInDiagonal(EDiagonal.NW_SO);
+    const diagNO_SW = this.damesInDiagonal(EDiagonal.NO_SW);
+
+    // steht schon eine Dame in der Diagonale NW_SO ?
+    const damesInDiagonalNW_SO = diagNW_SO.reduce(
+      (acc, act) => (act ? ++acc : acc),
+      0,
+    );
+
+    // steht schon eine Dame in der Diagonale NW_SO ?
+    const damesInDiagonalNO_SW = diagNO_SW.reduce(
+      (acc, act) => (act ? ++acc : acc),
+      0,
+    );
+
+    if (damesInDiagonalNW_SO > 1)
+      this.logger.error(`diagNW_SO occupied: ${this.modelPosition}`);
+    if (damesInDiagonalNO_SW > 1)
+      this.logger.error(`diagNO_SW occupied: ${this.modelPosition}`);
+
+    return damesInDiagonalNW_SO > 1 || damesInDiagonalNO_SW > 1;
+  };
+
+  // darf hier eine Dame stehen ?
+  positionPossible = (): boolean => {
+    const rp = this.rowProhibited();
+    const cp = this.colProhibited();
+    const dp = this.diagonalsProhibited();
+    const positionOk = !rp && !cp && !dp;
+
+    if (positionOk)
+      this.logger.log(`free: ${JSON.stringify(this.modelPosition)}`);
+
+    return positionOk;
+  };
+
+  // Dame auf das Feld platzieren
+  applyPosition = (): MatrixPosition => {
+    this.logger.warn(`apply: ${JSON.stringify(this.modelPosition)}`);
+    this.nDamesMatrix[this.modelPosition.row][this.modelPosition.col] = true;
+    return this.modelPosition;
+  };
+
+  // letzte Dame vom Feld nehmen
+  discardPosition = (): MatrixPosition => {
+    this.nDamesMatrix[this.modelPosition.row][this.modelPosition.col] = false;
+    return this.modelPosition;
+  };
+}
diff --git a/apps/n-dame-problem/src/n-dame-problem.controller.ts b/apps/n-dame-problem/src/n-dame-problem.controller.ts
index fe0f814..4005c36 100644
--- a/apps/n-dame-problem/src/n-dame-problem.controller.ts
+++ b/apps/n-dame-problem/src/n-dame-problem.controller.ts
@@ -1,12 +1,30 @@
-import { Controller, Get } from '@nestjs/common';
+import {
+  Controller,
+  DefaultValuePipe,
+  Get,
+  ParseIntPipe,
+  Query,
+} from '@nestjs/common';
 import { NDameProblemService } from './n-dame-problem.service';
 
 @Controller()
 export class NDameProblemController {
   constructor(private readonly nDameProblemService: NDameProblemService) {}
 
-  @Get()
+  @Get('/hello')
   getHello(): string {
     return this.nDameProblemService.getHello();
   }
+
+  @Get('/model')
+  getModel(
+    @Query('field', new DefaultValuePipe(-1), ParseIntPipe) field: number,
+  ): boolean[][] {
+    return this.nDameProblemService.getModel(field);
+  }
+
+  @Get('/backtracking')
+  getBacktracking() {
+    return this.nDameProblemService.getBacktracking();
+  }
 }
diff --git a/apps/n-dame-problem/src/n-dame-problem.service.ts b/apps/n-dame-problem/src/n-dame-problem.service.ts
index 5d4bc4b..1ccd78e 100644
--- a/apps/n-dame-problem/src/n-dame-problem.service.ts
+++ b/apps/n-dame-problem/src/n-dame-problem.service.ts
@@ -1,7 +1,48 @@
-import { Injectable } from '@nestjs/common';
+import { Injectable, Logger } from '@nestjs/common';
+import { NDameModel } from './n-dame-model';
+import { NDameBacktracking } from './n-dame-backtracking';
 
 @Injectable()
 export class NDameProblemService {
+  private readonly logger = new Logger(this.constructor.name);
+  private readonly MODEL_SIZE = 5;
+
+  getBacktracking(): NDameBacktracking {
+    const backTracking = new NDameBacktracking(4);
+
+    this.logger.log(`${backTracking.options()}`);
+    backTracking.solved();
+
+    return backTracking;
+  }
+
+  getModel(field: number): boolean[][] {
+    const model = new NDameModel(this.MODEL_SIZE);
+    const modelFieldCount = this.MODEL_SIZE * this.MODEL_SIZE;
+    const rndFields = [];
+
+    // geben wir keine FeldNr. an, dann die Zufallsreihe
+    if (field === -1)
+      for (var i = 0; i < this.MODEL_SIZE; i++)
+        rndFields.push(Math.floor(Math.random() * modelFieldCount));
+    else rndFields.push(field);
+
+    this.logger.fatal(`[${rndFields.toString()}]`);
+
+    for (var i = 0; i < modelFieldCount; i++) {
+      const nxtPos = model.nextPosition();
+
+      if (rndFields.includes(i)) {
+        model.applyPosition();
+        model.positionPossible();
+      }
+
+      // this.logger.verbose(`${i + 1} - ${JSON.stringify(nxtPos)}`);
+    }
+
+    return model.matrix;
+  }
+
   getHello(): string {
     return 'Hello World!';
   }
diff --git a/libs/backtracking-lib/src/backtracker.spec.ts b/libs/backtracking-lib/src/backtracker.spec.ts
new file mode 100644
index 0000000..fc3ee1e
--- /dev/null
+++ b/libs/backtracking-lib/src/backtracker.spec.ts
@@ -0,0 +1,7 @@
+import { Backtracker } from './backtracker';
+
+describe('Backtracker', () => {
+  it('should be defined', () => {
+    expect(new Backtracker()).toBeDefined();
+  });
+});
diff --git a/libs/backtracking-lib/src/backtracker.ts b/libs/backtracking-lib/src/backtracker.ts
new file mode 100644
index 0000000..0c7eb46
--- /dev/null
+++ b/libs/backtracking-lib/src/backtracker.ts
@@ -0,0 +1,26 @@
+import { IBacktracking } from './backtracking.interface';
+
+export class Backtracker {
+  findSolution = (dataObject: IBacktracking): boolean => {
+    if (dataObject.solved()) return true;
+
+    // nächstes freie Position suchen
+    dataObject.nextPosition();
+
+    dataObject.options().forEach((option) => {
+      // darf die Option hier eingestellt werden ?
+      if (dataObject.positionPossible()) {
+        dataObject.applyPosition();
+
+        // Lösung mit dem neu konfigurierten dataObject finden
+        const solved: boolean = this.findSolution(dataObject);
+
+        if (solved) return true;
+
+        dataObject.discardPosition();
+      }
+    });
+
+    return false;
+  };
+}
diff --git a/libs/backtracking-lib/src/backtracking-lib.service.ts b/libs/backtracking-lib/src/backtracking-lib.service.ts
index de5f68d..b4a48f3 100644
--- a/libs/backtracking-lib/src/backtracking-lib.service.ts
+++ b/libs/backtracking-lib/src/backtracking-lib.service.ts
@@ -1,4 +1,27 @@
 import { Injectable } from '@nestjs/common';
 
+/**
+ * PSEUDO-CODE:
+ *
+void FIND_SOLUTIONS (Parameter):
+
+  wenn (gültige Lösung ):
+    Bewahren Sie die Lösung auf
+    Zurückkehren (gelöst)
+
+  für (alle Auswahlmöglichkeiten ):
+    wenn (gültige Auswahl ):
+      ANWENDEN ( Auswahl )
+
+      FIND_SOLUTIONS (Parameter)
+      wenn (gültige Lösung ):
+        Bewahren Sie die Lösung auf
+        Zurückkehren (gelöst)
+
+      BACKTRACK ( Auswahl entfernen )
+
+  Zurückkehren (nicht gelöst)
+ */
+
 @Injectable()
 export class BacktrackingLibService {}
diff --git a/libs/backtracking-lib/src/backtracking.interface.ts b/libs/backtracking-lib/src/backtracking.interface.ts
new file mode 100644
index 0000000..873a52c
--- /dev/null
+++ b/libs/backtracking-lib/src/backtracking.interface.ts
@@ -0,0 +1,10 @@
+import { MatrixPosition } from './matrix-position';
+
+export interface IBacktracking {
+  options: () => Array<any>;
+  solved: () => boolean;
+  nextPosition: () => MatrixPosition;
+  positionPossible: () => boolean;
+  applyPosition: () => MatrixPosition;
+  discardPosition: () => MatrixPosition;
+}
diff --git a/libs/backtracking-lib/src/matrix-position.ts b/libs/backtracking-lib/src/matrix-position.ts
new file mode 100644
index 0000000..f323952
--- /dev/null
+++ b/libs/backtracking-lib/src/matrix-position.ts
@@ -0,0 +1,25 @@
+export class MatrixPosition {
+  constructor(
+    private _row: number,
+    private _col: number,
+  ) {}
+
+  public get row() {
+    return this._row;
+  }
+  public set row(r: number) {
+    this._row = r;
+  }
+
+  public get col() {
+    return this._col;
+  }
+
+  public set col(c: number) {
+    this._col = c;
+  }
+
+  public toString() {
+    return `[${this._row},${this._col}]`;
+  }
+}
diff --git a/package.json b/package.json
index b66b3fc..3b59341 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "backtracking",
-  "version": "0.9.0",
+  "version": "1.0.0",
   "description": "",
   "author": "",
   "private": true,