LeetCode 64. Minimum Path Sum

最大值最小值問題,dp矩陣型問題,保存每一步的狀態, 首先初始化第一行和第一列,然後填充中間的值,dp[i][j] = grid[i][j]+min(dp[i-1][j],dp[i][j-1])

class Solution {
public:
    int minPathSum(vector<vector<int>>& grid) {
        int col = grid[0].size();
        int row = grid.size();
        int dp[row+1][col+1];
        memset(dp,0,sizeof(dp));
        dp[0][0] = grid[0][0];
        for(int i = 1; i < col; i++)
            dp[0][i] = dp[0][i-1] + grid[0][i];
        for(int j = 1; j < row; j++)
            dp[j][0] = dp[j-1][0] + grid[j][0];
        for(int i = 1; i < col; i++){
            for(int j = 1; j < row; j++){
                dp[j][i] = min(dp[j-1][i],dp[j][i-1])+grid[j][i];
            }
        }
        return dp[row-1][col-1];
    }
};