120. Triangle 以及一个多维vector如何初始化

1.刚开始result的初始化写的是vector<vector<int>> result,然后再去对result[0][0] = triangle[0][0]赋值，一直报错。老问题了！

2.多维vector的初始化：

vector<vector<int>> result(height,vector<int>(width))

class Solution {
public:
    int minimumTotal(vector<vector<int>>& triangle) {
        int height = triangle.size();
        if(height <= 0)
            return 0;
        if(height == 1)
            return triangle[0][0];
        int width = triangle[height-1].size();
        vector<vector<int>> result(height,vector<int>(width));
        result[0][0] = triangle[0][0];
        for(int i = 1;i < height;i++){
            width = triangle[i].size();
            for(int j = 0;j < width;j++){
                if(j !=0 && j != (width-1)){
                    result[i][j] = min(result[i-1][j] + triangle[i][j],result[i-1][j-1] + triangle[i][j]);
                }
                else if(j == 0)
                    result[i][j] = result[i-1][j] + triangle[i][j];
                else
                    result[i][j] = result[i-1][j-1] + triangle[i][j];
            }
        }
        int min_num = 0x7fffffff;
        for(int i = 0;i < triangle[height-1].size();i++){
            if(min_num > result[height-1][i])
                min_num = result[height-1][i];
        }
        return min_num;
    }
};

 简化版

class Solution {
public:
    int minimumTotal(vector<vector<int>>& triangle) {
        int length = triangle.size();
        vector<vector<int>> result(length,vector<int>(length));
        result[0][0] = triangle[0][0];
        for(int i = 1;i < length;i++){
            for(int j = 0;j <= i;j++){
                if(j == 0)
                    result[i][j] = result[i-1][j] + triangle[i][j];
                else if(j == i)
                    result[i][j] = result[i-1][j-1] + triangle[i][j];
                else
                    result[i][j] = min(result[i-1][j],result[i-1][j-1]) + triangle[i][j];
            }
        }
        int min_num = 0x7FFFFFFF;
        for(int i = 0;i < length;i++){
            if(result[length-1][i] < min_num)
                min_num = result[length-1][i];
        }
        return min_num;
    }
};