Java for LeetCode 120 Triangle

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).

解题思路：

DP问题，用一个dp数组滚动下来即可，JAVA实现如下：

    public int minimumTotal(List<List<Integer>> triangle) {
		int[] dp = new int[triangle.size()];
		dp[0]=triangle.get(0).get(0);
		if(triangle.size()>=2){
			dp[1]=triangle.get(1).get(1)+dp[0];
			dp[0]+=triangle.get(1).get(0);
		}
		for (int i=2;i<triangle.size();i++) {
			int left = dp[0];
			int right = dp[1];
			dp[0] += triangle.get(i).get(0);
			for (int j = 1; j <= i - 1; j++) {
				dp[j] = triangle.get(i).get(j) + Math.min(left, right);
				left = right;
				right = dp[j + 1];
			}
			dp[i] = left + triangle.get(i).get(i);
			left = dp[0];
			right = dp[1];
		}
		for (int i = 0; i < dp.length - 1; i++)
			if (dp[i] < dp[i + 1])
				dp[i + 1] = dp[i];
		return dp[dp.length - 1];
    }