Algorithm
Problem Nmae: 119. Pascal's Triangle II
Given an integer rowIndex, return the rowIndexth (0-indexed) row of the Pascal's triangle.
In Pascal's triangle, each number is the sum of the two numbers directly above it as shown:
Example 1:
Input: rowIndex = 3 Output: [1,3,3,1]
Example 2:
Input: rowIndex = 0 Output: [1]
Example 3:
Input: rowIndex = 1 Output: [1,1]
Code Examples
#1 Code Example with C Programming
Code -
C Programming
#include <stdio.h>
#include <stdlib.h>
int *getRow(int rowIndex) {
int k = rowIndex;
int *ans = (int *)calloc(k + 1, sizeof(int));
int i, j;
int prev = 0, cur = 0;
ans[0] = 1;
for (i = 1; i < k + 1; i++) {
prev = ans[0];
for (j = 1; j < i; j++) {
cur = ans[j];
ans[j] += prev;
prev = cur;
}
ans[i] = 1;
}
return ans;
}
int main() {
int k = 5;
int *ans = getRow(k);
int i;
for (i = 0; i < k + 1; i++) {
printf("%d ", ans[i]);
}
printf("\n");
return 0;
}
Input
Output
#2 Code Example with C++ Programming
Code -
C++ Programming
class Solution {
public:
vector<int> getRow(int rowIndex) {
if(rowIndex == 0) return {1};
auto v = getRow(rowIndex - 1);
int n = v.size();
for(int i = 1; i < n; i++)
v[i] = (i < = n/2) ? v[i] + v[n - i] : v[n - i];
v.push_back(1>;
return v;
}
};
Input
Output
#3 Code Example with Java Programming
Code -
Java Programming
class Solution {
public List getRow(int rowIndex) {
List lastRow = new ArrayList<>();
for (int i = 0; i < = rowIndex; i++) {
List copy = new ArrayList<>(lastRow);
lastRow.clear();
for (int j = 0; j < = i; j++) {
if (j == 0 || j == i) {
lastRow.add(1);
} else {
lastRow.add(copy.get(j - 1) + copy.get(j));
}
}
}
return lastRow;
}
}
Input
Output
#4 Code Example with Javascript Programming
Code -
Javascript Programming
const getRow = function(rowIndex) {
if (!rowIndex) return [1];
if (rowIndex === 1) return [1, 1];
const res = [1, 1];
for (let i = 2; i < = rowIndex; i++) {
res[i] = 1;
for (let j = i - 1; j >= 1; j--) {
res[j] = res[j] + res[j - 1];
}
}
return res;
};
Input
Output
#5 Code Example with Python Programming
Code -
Python Programming
class Solution:
def getRow(self, rowIndex: int, row = [1]) -> List[int]:
return self.getRow(rowIndex - 1, [a + b for a, b in zip([0] + row, row + [0])]) if rowIndex else row
Input
Output
#6 Code Example with C# Programming
Code -
C# Programming
using System.Collections.Generic;
namespace LeetCode
{
public class _119_PascalsTriangle2
{
public IList < int> GetRow(int rowIndex)
{
var result = new int[rowIndex + 1];
result[0] = 1;
if (rowIndex == 0) return result;
for (int i = 1; i < = rowIndex; i++)
for (int j = i; j > 0; j--)
result[j] = result[j - 1] + result[j];
return result;
}
}
}
Input
Output