LeetCode120——Triangle

最新推荐文章于 2019-10-02 10:18:42 发布

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最新推荐文章于 2019-10-02 10:18:42 发布

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本文介绍了一种求解三角形结构中从顶点到底边的最小路径和的方法。通过逆向迭代，从倒数第二行开始更新每条边的权值，确保每个节点保存的是到达底边的最小路径和。最终，顶点的值即为最小路径和。

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.

实现：

class Solution {
public:
int minimumTotal(vector<vector<int>>& triangle) {
int n = triangle.size();
for (int i=n-2; i >=0; i--) {
for (int j = 0; j < triangle[i].size(); j++) {
triangle[i][j] += triangle[i+1][j] < triangle[i+1][j+1] ? triangle[i+1][j] : triangle[i+1][j+1];
}
}
return triangle[0][0];
}
};