120. Triangle

可以用一个数组就能解决，思路一样的懒得写了，刚开始以为左中右都能走，结果是只能走右和中，因为我把三角化成矩阵的时候想错了，走的路径是针对三角的 




class Solution {
public:
    int minimumTotal(vector<vector<int>>& triangle) {
    if (triangle.empty())return 0;
        int n = triangle.size();
        vector<vector<int>> path(n, vector<int>(n, 0));
        path[0][0] = triangle[0][0];
        for (int i = 1;i < n;i++) {
            for (int j = 0;j < triangle[i].size();j++) {
                if (j == 0)path[i][j] = path[i-1][j] + triangle[i][j];
                else if (j == i)path[i][j] = path[i - 1][j - 1] + triangle[i][j];
                else  path[i][j] = min(path[i - 1][j] + triangle[i][j], path[i - 1][j - 1] + triangle[i][j]);
            
            }
            
        }
        int res = path[n - 1][0];
        for (int i = 0; i < triangle[n - 1].size(); ++i) {
            res = min(res, path[n - 1][i]);
        }
        return res;
    }
};

Runtime: 4 ms, faster than 99.61% of C++ online submissions for Triangle.