LeetCode: Triangle

基本一次过

class Solution {
public:
    int minimumTotal(vector<vector<int> > &triangle) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if (!triangle.size()) return 0;
        if (triangle.size() == 1) return triangle[0][0];
        vector<int> pre = triangle[0];
        for (int i = 1; i < triangle.size(); i++) {
            vector<int> tmp = pre;
            for (int j = 0; j < pre.size(); j++) {
                if (!j) tmp[j] = pre[j] + triangle[i][j];
                else tmp[j] = min(pre[j-1], pre[j]) + triangle[i][j];
            }
            tmp.push_back(triangle[i][i]+pre[pre.size()-1]);
            pre = tmp;
        }
        int ret = pre[0];
        for (int i = 1; i < pre.size(); i++) ret = min(ret, pre[i]);
        return ret;
    }
};