Question avoidroads of topcoder

general
1

How can I do the question avoidroads of topcoder TopCoder Statistics - Problem Statement

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I have no idea, why this round is not listed in Analysis page.

Maybe you can get some ideas (only code) from forum.

3

Thanks betlista but could anyone explain the approach

4

Direct DP problem : Since we have to use exactly width+height many steps, therefore cannot more left or down. Let dp[i][j] be number of ways from (i,j) to (width,height).
Then dp[i][j] = (if (i j i+1 j) is not in list) dp[i+1][j] 

+ (if (i j i j+1) is not in list) dp[i][j+1]

PS: the official editorial is here.