LeetCode120 三角形

最新推荐文章于 2021-02-20 10:57:22 发布

原创最新推荐文章于 2021-02-20 10:57:22 发布 · 188 阅读

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本文介绍了一种求解三角形结构中从顶点到底部的最小路径和问题的高效算法。通过动态规划方法，利用O(n)额外空间，实现了对任意大小三角形的有效求解。示例中给出了具体实现代码。

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Given a triangle, find the minimum path sum from top to bottom. Each step you may move to adjacent numbers on the row below.

For example, given the following triangle

[
[2],
[3,4],
[6,5,7],
[4,1,8,3]
]
The minimum path sum from top to bottom is 11 (i.e., 2 + 3 + 5 + 1 = 11).

Note:

Bonus point if you are able to do this using only O(n) extra space, where n is the total number of rows in the triangle.

class Solution {
    public int minimumTotal(List<List<Integer>> triangle) {
        int[] A = new int[triangle.size() + 1];
        for(int i = triangle.size() - 1; i >= 0; i--){
            for(int j = 0; j <= i; j++){
                A[j] = Math.min(A[j], A[j+1]) + triangle.get(i).get(j);
            }
        }
        return A[0];
    }
}