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LeetCode:Triangle

时间:2016-06-12 02:18:12      阅读:124      评论:0      收藏:0      [点我收藏+]

标签:

Triangle




Total Accepted: 71791 Total Submissions: 235313 Difficulty: Medium

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.

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思路:

从下往上dp。


c++ code:

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


LeetCode:Triangle

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原文地址:http://blog.csdn.net/itismelzp/article/details/51628994

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