[LeetCode] 64. Minimum Path Sum and minimum path (Medium) (JAVA)
Topic Address: https://leetcode.com/problems/minimum-path-sum/
Subject description:
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.
Example:
Input:
[
[1,3,1],
[1,5,1],
[4,2,1]
]
Output: 7
Explanation: Because the path 1→3→1→1→1 minimizes the sum.
Subject to the effect
Given a non-negative integer of mxn grid, find a path from left to bottom right, so that the sum of the minimum number of paths.
Note: you can only move one step down or to the right.
Problem-solving approach
A question and the same solution: [] 63. Unique Paths II LeetCode different path II (Medium) (JAVA)
1, dynamic programming, traversing from the back
2, front and left of the minimum value comparison
class Solution {
public int minPathSum(int[][] grid) {
if (grid.length == 0 || grid[0].length == 0) return 0;
int[][] dp = new int[grid.length][grid[0].length];
for (int i = grid.length - 1; i >= 0; i--) {
for (int j = grid[0].length - 1; j>= 0; j--) {
if (i == grid.length - 1 && j == grid[0].length - 1) {
dp[i][j] = grid[i][j];
} else if (i == grid.length - 1) {
dp[i][j] = grid[i][j] + dp[i][j + 1];
} else if (j == grid[0].length - 1) {
dp[i][j] = grid[i][j] + dp[i + 1][j];
} else {
dp[i][j] = grid[i][j] + (dp[i + 1][j] > dp[i][j + 1] ? dp[i][j + 1] : dp[i + 1][j]);
}
}
}
return dp[0][0];
}
}
When execution: 4 ms, beat the 33.37% of all users to submit in Java
memory consumption: 42.5 MB, defeated 20.81% of all users to submit in Java
