# Get wrong answer with Java, can anybody tell me why?

• ``````public class Solution {
public  ArrayList<ArrayList<Integer>> generate(int numRows) {
ArrayList<ArrayList<Integer>> res = new ArrayList<ArrayList<Integer>>();
for (int i = 1; i < numRows + 1; i++) {
}
return res;

}

private int factorial(int n) {
if (n < 0) return 0;
if (n == 0) return 1;
else
return n * factorial(n-1);
}

private int conbination(int n, int k) {
return factorial(n)/(factorial(n - k) * factorial(k));
}

private ArrayList<Integer> eachLine(int i) {
ArrayList<Integer> list = new ArrayList<Integer>();
for (int j = 0; j < i + 1; j++) {
}
return list;
}

}
``````

Submission Result: Wrong Answer

Input: 15
Output: [[1],[1,1],[1,2,1],[1,3,3,1],[1,4,6,4,1],[1,5,10,10,5,1],[1,6,15,20,15,6,1],[1,7,21,35,35,21,7,1],[1,8,28,56,70,56,28,8,1],[1,9,36,84,126,126,84,36,9,1],[1,10,45,120,210,252,210,120,45,10,1],[1,11,55,165,330,462,462,330,165,55,11,1],[1,12,66,220,495,792,924,792,495,220,66,12,1],[1,4,24,88,221,399,532,532,399,221,88,24,4,1],[1,0,1,5,14,29,44,50,44,29,14,5,1,0,1]]

Expected: [[1],[1,1],[1,2,1],[1,3,3,1],[1,4,6,4,1],[1,5,10,10,5,1],[1,6,15,20,15,6,1],[1,7,21,35,35,21,7,1],[1,8,28,56,70,56,28,8,1],[1,9,36,84,126,126,84,36,9,1],[1,10,45,120,210,252,210,120,45,10,1],[1,11,55,165,330,462,462,330,165,55,11,1],[1,12,66,220,495,792,924,792,495,220,66,12,1],[1,13,78,286,715,1287,1716,1716,1287,715,286,78,13,1],[1,14,91,364,1001,2002,3003,3432,3003,2002,1001,364,91,14,1]]

• Probably hit integer overflow 13! = 6227020800 > 2^31.

• thanks a lot ~

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