Question avoidroads of topcoder

How can I do the question avoidroads of topcoder

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

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

Thanks betlista but could anyone explain the approach

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.