leetcode题解（二十八）：64. Minimum Path Sum

题意：给一个m*n的格子，求左上到右下的最小和
Input:
[
[1,3,1],
[1,5,1],
[4,2,1]
]
Output: 7
Explanation: Because the path 1→3→1→1→1 minimizes the sum.
思路和unique path那道题差不多，都是更新二维数组

public int minPathSum(int[][] grid) {
	//行
	int m = grid.length;// row
	//列
	int n = grid[0].length; // column
	for (int i = 0; i < m; i++) {
		for (int j = 0; j < n; j++) {
			//如果i为0j不为0，即第一行
			if (i == 0 && j != 0) {
				//更新第一行
				grid[i][j] = grid[i][j] + grid[i][j - 1];
				//更新第一列
			} else if (i != 0 && j == 0) {
				grid[i][j] = grid[i][j] + grid[i - 1][j];
				//初始化第一个格子
			} else if (i == 0 && j == 0) {
				grid[i][j] = grid[i][j];
				//剩下就是普通情况，选最小的路走过来
			} else {
				grid[i][j] = Math.min(grid[i][j - 1], grid[i - 1][j])
						+ grid[i][j];
			}
		}
	}

	return grid[m - 1][n - 1];
}