Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its path.
Note: You can only move either down or right at any point in time.
建立一个背包dpm，其中dpi表示从grid0到gridi的最小和。
代码语言：txt复制 public int minPathSum(int[][] grid) {
if (grid == null || grid[0] == null) {
return 0;
}
int m = grid.length;
int n = grid[0].length;
int[][] dp = new int[m][n];
dp[0][0] = grid[0][0];
for (int y = 1; y < n; y ) {
dp[0][y] = dp[0][y - 1] grid[0][y];
}
for (int x = 1; x < m; x ) {
dp[x][0] = dp[x - 1][0] grid[x][0];
}
for (int y = 1; y < n; y ) {
for (int x = 1; x < m; x ) {
int min = Math.min(dp[x - 1][y], dp[x][y - 1]);
dp[x][y] = min grid[x][y];
}
}
return dp[m - 1][n - 1];
}
