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pascals-triangle.java
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31 lines (25 loc) · 871 Bytes
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/*Question:-Given an integer numRows, return the first numRows of Pascal's triangle.
In Pascal's triangle, each number is the sum of the two numbers directly above it as shown:
image address:-https://upload.wikimedia.org/wikipedia/commons/0/0d/PascalTriangleAnimated2.gif
Example 1:
Input: numRows = 5
Output: [[1],[1,1],[1,2,1],[1,3,3,1],[1,4,6,4,1]]*/
//Solution//
class Solution {
public List<List<Integer>> generate(int numRows) {
List<List<Integer>> res = new ArrayList<List<Integer>>();
List<Integer> row, pre = null;
for (int i = 0; i < numRows; ++i) {
row = new ArrayList<Integer>();
for (int j = 0; j <= i; ++j)
if (j == 0 || j == i)
row.add(1);
else
row.add(pre.get(j - 1) + pre.get(j));
pre = row;
res.add(row);
}
return res;
}
}
//Submission link:-https://leetcode.com/submissions/detail/799641385/