[LintCode/LeetCode] Minimum Path Sum

CntChen 發布于2019-08-14 15:28 / 2338人閱讀

摘要：遍歷整個矩陣，對于，取上方和左邊較小值，與相加可得該點最小值。

Problem

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.

You can only move either down or right at any point in time.

Note

遍歷整個矩陣，對于dp[i][j]，取上方dp[i-1][j]和左邊dp[i][j-1]較小值，與grid[i][j]相加可得該點最小值。

Solution

public class Solution {
    public int minPathSum(int[][] grid) {
        int m = grid.length, n = grid[0].length;
        int[][] dp = new int[m][n];
        dp[0][0] = grid[0][0];
        for (int i = 1; i < m; i++) {
            dp[i][0] = dp[i-1][0] + grid[i][0];
        }
        for (int i = 1; i < n; i++) {
            dp[0][i] = dp[0][i-1] + grid[0][i];
        }
        for (int i = 1; i < m; i++) {
            for (int j = 1; j < n; j++) {
                dp[i][j] = Math.min(dp[i-1][j], dp[i][j-1]) + grid[i][j];
            }
        }
        return dp[m-1][n-1];
    }
}

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