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Commitdf17e29

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Add backtracking solution to JumpGame.
1 parentaacd779 commitdf17e29

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4 files changed

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4 files changed

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importbtJumpGamefrom'../btJumpGame';
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describe('btJumpGame',()=>{
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it('should solve Jump Game problem in backtracking manner',()=>{
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expect(btJumpGame([1,0])).toBeTruthy();
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expect(btJumpGame([100,0])).toBeTruthy();
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expect(btJumpGame([2,3,1,1,4])).toBeTruthy();
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expect(btJumpGame([1,1,1,1,1])).toBeTruthy();
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expect(btJumpGame([1,1,1,10,1])).toBeTruthy();
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expect(btJumpGame([1,5,2,1,0,2,0])).toBeTruthy();
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expect(btJumpGame([1,0,1])).toBeFalsy();
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expect(btJumpGame([3,2,1,0,4])).toBeFalsy();
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expect(btJumpGame([0,0,0,0,0])).toBeFalsy();
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expect(btJumpGame([5,4,3,2,1,0,0])).toBeFalsy();
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});
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});

‎src/algorithms/uncategorized/jump-game/__test__/grdJumpGame.test.js

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expect(grdJumpGame([100,0])).toBeTruthy();
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expect(grdJumpGame([2,3,1,1,4])).toBeTruthy();
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expect(grdJumpGame([1,1,1,1,1])).toBeTruthy();
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expect(grdJumpGame([1,1,1,10,1])).toBeTruthy();
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expect(grdJumpGame([1,5,2,1,0,2,0])).toBeTruthy();
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expect(grdJumpGame([1,0,1])).toBeFalsy();
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/**
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* BACKTRACKING approach of solving Jump Game.
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*
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*@param {number[]} numbers - array of possible jump length.
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*@param {number} startIndex - index from where we start jumping.
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*@param {number[]} currentJumps - current jumps path.
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*@return {boolean}
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*/
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exportdefaultfunctionbtJumpGame(numbers,startIndex=0,currentJumps=[]){
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if(startIndex===numbers.length-1){
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// We've jumped directly to last cell. This situation is a solution.
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returntrue;
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}
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// Check what the longest jump we could make from current position.
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// We don't need to jump beyond the array.
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constmaxJumpLength=Math.min(
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numbers[startIndex],// Jump is within array.
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numbers.length-1-startIndex,// Jump goes beyond array.
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);
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// Let's start jumping from startIndex and see whether any
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// jump is successful and has reached the end of the array.
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for(letjumpLength=maxJumpLength;jumpLength>0;jumpLength-=1){
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// Try next jump.
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constnextIndex=startIndex+jumpLength;
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currentJumps.push(nextIndex);
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constisJumpSuccessful=btJumpGame(numbers,nextIndex,currentJumps);
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// Check if current jump was successful.
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if(isJumpSuccessful){
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returntrue;
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}
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// BACKTRACKING.
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// If previous jump wasn't successful then retreat and try the next one.
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currentJumps.pop();
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}
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returnfalse;
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}

‎src/algorithms/uncategorized/jump-game/grdJumpGame.js

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* GREEDY approach of solving Jump Game.
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*
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*@param {number[]} numbers - array of possible jump length.
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*@return {boolean}
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*/
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exportdefaultfunctiongrdJumpGame(numbers){
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// The "good" cell is a cell from which we may jump to the last cell of the numbers array.

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