Difficulties in coping means of more than one algorithm with mean in Java

I have a problem: I have the time it takes for the BFS, DFS and A * algorithms to solve 15 games according to their own difficulties. There are several games for each level of difficulty). He is able to calculate the medium for BFS but not for others and I do not understand why ...

Can you help me understand this problem?

Here is the code to write the results in writer.

                    PrintWriter writer = new PrintWriter("result.txt", "UTF-8");
                    writer.println("runTime DFS" + runTimesDFS);
                    writer.println("run time BFS : " + runTimesBFS);
                    writer.println("run Times AStar1" + runTimesAStar1);
                    writer.println("run Times AStar2" + runTimesAStar2);

                    writer.close();

                    meanDFS.addLast((double)mean(runTimesDFS));
                    meanBFS.addLast((double)mean(runTimesBFS));
                    meanAStar1.addLast((double)mean(runTimesAStar1));
                    meanAStar2.addLast((double)mean(runTimesAStar2));

                    PrintWriter writer1 = new PrintWriter("mean.txt", "UTF-8");
                    writer1.print("d\t");
                    writer1.print("BFS\t");
                    writer1.print("DFS\t");
                    writer1.print("A*(h1)\t");
                    writer1.println("A*(h2)\t");

                    for(int i =0;i<problemSize;i++){
                        if(i<=1||i==3)continue;
                        if(i==2){
                            writer1.print(i+"\t");
                            writer1.print(meanDFS.get(0)+"\t");
                            writer1.print(meanBFS.get(0)+"\t");
                            writer1.print(meanAStar1.get(0)+"\t");
                            writer1.println(meanAStar2.get(0)+"\t");
                            continue;
                        }
                        writer1.print(i+"\t");
                        writer1.print(meanDFS.get(i-2)+"\t");
                        writer1.print(meanBFS.get(i-2)+"\t");
                        writer1.print(meanAStar1.get(i-2)+"\t");
                        writer1.println(meanAStar2.get(i-2)+"\t");


                    }
                    writer1.close();

Here are the results of result.txt :

runTime DFS[1002275500, -1, 30671, 30671, 201439, 201439, 130626, 130626, 613260, 613260, 150597, 150597, 230334797, 230334797, 119078, 119078, 1000880068, -1, 1000898024, -1, 1001873664, -1, 1001111309, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1]
run time BFS : [-1, 60196, 234840, 230154, 856084, 1249830, 223248477, 229813, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1]
run Times AStar1[316141, 100123, 599730, 621865, 2437748, 891661, 441231, 3304836, 448971, 10450851, 1031470, 1364444, 2150342, 1236668, 2398004, 1012777, 3577413, 930346, 1342229, 1287399, 833987, 923909, 991805, 736422, 1089391, 1529460, 2102012, 1818439, 2150166, 1362405, 2274912, 1821755, 1783043, 1497208, 1394854, 2566307, 2116257, 16251554, 1131473, 977269, 12538716, 1937947, 6316898, 1526144, 1015829, 2391290, 1061151, 4212817, 3203434, 7697831, 4004167, 11981158, 18767610, 10363610, 7720948, 5812849, 5035632, 5151903, 4242567, 11205300, 19161910, 7364846, 8246685, 10374449, 6356850, 3127472, 4460724, 4658711, 34526503, 15950820, 19204683, 3039093, 4819100, 4231508, 2774177, 3387505, 2192512, 3775054, 8767586, 6299780, 4685219, 8116913, 2962584, 3138993, 4242035]
run Times AStar2[307918, 111674, 502747, 503270, 6069636, 845279, 413490, 3172552, 544288, 2758568, 1050064, 2634507, 1503979, 1257892, 1886224, 1020397, 5118195, 667317, 1954363, 1891691, 583031, 792316, 844829, 691413, 811217, 1490068, 2100134, 1852067, 1626993, 1375678, 1540837, 2324116, 1415832, 2015665, 1459347, 2592766, 1630265, 1423187, 1100070, 13949628, 10510684, 1581410, 5928335, 3257547, 1009206, 1794131, 1033910, 4065738, 5294198, 4902085, 39496174, 6987337, 8793467, 15267404, 7290771, 4825445, 4212857, 8364815, 2500645, 22345290, 13907331, 5114238, 6964583, 12030011, 4264531, 3634794, 4771136, 2367023, 15850205, 15110779, 4679247, 3816970, 8592082, 3839918, 2827192, 3510492, 68274340, 10894103, 19928970, 5991074, 4862344, 4680440, 3192033, 3180315, 53607999]

Here is the results of mean.txt file

d   BFS DFS A*(h1)  A*(h2)  
2   0.25    0.0 0.0 0.0 
4   0.07142857142857142 0.0 0.0 0.0 
5   0.1111111111111111  0.0 0.0 0.0 
6   0.13513513513513514 0.0 0.0 0.0 
7   0.0847457627118644  0.0 0.0 0.0 
8   0.05154639175257732 0.0 0.0 0.0 
9   0.05154639175257732 0.0 0.0 0.0 
10  0.05154639175257732 0.0 0.0 0.0 
11  0.05154639175257732 0.0 0.0 0.0 
12  0.05154639175257732 0.0 0.0 0.0 
13  0.05154639175257732 0.0 0.0 0.0 
14  0.05154639175257732 0.0 0.0 0.0 
15  0.05154639175257732 0.0 0.0 0.0 
16  0.05154639175257732 0.0 0.0 0.0 
17  0.05154639175257732 0.0 0.0 0.0 
18  0.05154639175257732 0.0 0.0 0.0 
19  0.05154639175257732 0.0 0.0 0.0 
20  0.05154639175257732 0.0 0.0 0.0 
21  0.05154639175257732 0.0 0.0 0.0 
22  0.05154639175257732 0.0 0.0 0.0 
23  0.05154639175257732 0.0 0.0 0.0 
24  0.05154639175257732 0.0 0.0 0.0 
25  0.05154639175257732 0.0 0.0 0.0 
26  0.05154639175257732 0.0 0.0 0.0 
27  0.05154639175257732 0.0 0.0 0.0 
28  0.05154639175257732 0.0 0.0 0.0 
29  0.05154639175257732 0.0 0.0 0.0 
30  0.05154639175257732 0.0 0.0 0.0 
31  0.05154639175257732 0.0 0.0 0.0 

And here is the mean (List l)

    public static double mean(List<Long> l){
    long res=0;
    for (Long val: l)
        res+=val/1000000000;
    return (1.0*res) / l.size();
}