[LeetCode]Triangle

2015-01-26 23:13:10 · 作者: · 浏览: 3

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.

动态规划

public class Solution {
	int []f;
	public int minimumTotal(List
  
   > triangle) {
		int size = triangle.size();
        f = new int[(size+1)*(size)/2];
        f[0] = triangle.get(0).get(0);
        for(int i=1;i
   
    
深搜(超时)

public class Solution {
	int minRes = Integer.MAX_VALUE;
    public int minimumTotal(List
     
      > triangle) {
        minimumTotal(triangle,0,0,0);
        return minRes;
    }
    
    private void minimumTotal(List
      
       > triangle,int sum,int size,int column){ if(size==triangle.size()){ minRes = Math.min(sum, minRes); return; } sum += triangle.get(size).get(column); minimumTotal(triangle,sum,size+1,column); minimumTotal(triangle,sum,size+1,column+1); } }