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.
难度：medium
题目：给定一三角形数组，找出从上到下最小的路径和。每步只可以向下一行的相邻元素移动。
Runtime: 4 ms, faster than 87.60% of Java online submissions for Triangle.Memory Usage: 38.5 MB, less than 100.00% of Java online submissions for Triangle.
class Solution {
public int minimumTotal(List<List<Integer>> triangle) {
int m = triangle.size();
if (1 == m) {
return triangle.get(0).get(0);
}
int[][] table = new int[m][m];
for (int i = 0; i < m; i++) {
for (int j = 0; j <= i; j++) {
table[i][j] = triangle.get(i).get(j);
}
}
int result = table[0][0];
for (int i = 1; i < m; i++) {
result = table[i][0] + table[i – 1][0];
for (int j = 0; j <= i; j++) {
if (0 == j) {
table[i][j] += table[i – 1][j];
} else if (j == i) {
table[i][j] += table[i – 1][j – 1];
} else {
table[i][j] += Math.min(table[i – 1][j], table[i – 1][j – 1]);
}
result = Math.min(table[i][j], result);
}
}
return result;
}
}