vector< vector > dp; //initialize with -1 vector< vector > dist; //initialize with all dists between points vector lr, rl; //left-to-right and right-to-left paths int n; //number of points double get(int p1, int p2) { //call get(0, 0) to get length of shortest bitonic route int v = max(p1, p2) + 1; if (v == n - 1) return dist[p1][v] + dist[v][p2]; if (dp[p1][p2] > -0.5) return dp[p1][p2]; double tryLR = dist[p1][v] + get(v, p2), tryRl = dist[v][p2] + get(p1, v); if (tryLR < tryRL) lr.push_back(v); //reconstructs the path, pushes v to rl if the choice does not matter else rl.push_back(v); //change this if needed return min(tryLR, tryRL); }