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119. Pascal's Triangle II

119. Pascal's Triangle II

作者: SilentDawn | 来源:发表于2018-06-26 09:57 被阅读0次

Problem

Given a non-negative index k where k ≤ 33, return the kth index row of the Pascal's triangle.
Note that the row index starts from 0.

image.png
In Pascal's triangle, each number is the sum of the two numbers directly above it.

Example

Input: 3
Output: [1,3,3,1]

Follow up:
Could you optimize your algorithm to use only O(k) extra space?

Code

static int var= [](){
    std::ios::sync_with_stdio(false);
    cin.tie(NULL);
    return 0;
}();
class Solution {
public:
    vector<int> getRow(int rowIndex) {
        vector<int> res(rowIndex+1,0);
        if(rowIndex>=0)
            res[0] = 1;
        for(int i=0;i<=rowIndex;i++){
            for(int j=i;j>0;j--){
                res[j] += res[j-1];
            }
        }
        return res;
    }
};

Result

119. Pascal's Triangle II.png

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