(Medium) Minimum Fallig Path Sum LeetCode

 

 

class Solution {
    public int minFallingPathSum(int[][] A) {
        
        if(A== null|| A.length==0 || A[0].length ==0 ){
            return 0;
        }
        
        int n = A.length ;
        int m = A[0].length;
        
        int[][] dp = new int[n][m];
        
        // first row calculation
        
        for(int i = 0; i<m; i++){
            
            dp[0][i] =A[0][i];
        
        }
        
        for(int i = 1; i<n; i++){
            
            
            for(int j = 0; j<m; j++ ){
                
                //first column scenario
                if(j == 0){
                    
                    dp[i][j]= Math.min(dp[i-1][j],dp[i-1][j+1])+A[i][j];
                }
                
                //last column scenario
                else if (j ==m-1){
                    
                    dp[i][j]=Math.min(dp[i-1][j-1],dp[i-1][j])+A[i][j];
                }
                
                //non-border scenario
                
                else{
                    dp[i][j]=Math.min(dp[i-1][j-1],Math.min(dp[i-1][j],dp[i-1][j+1]))+A[i][j];
                    
                    
                    
                }
            }
        }
        
        int min = Integer.MAX_VALUE;
        for(int j = 0; j<m; j++){
            
            if(dp[n-1][j]<min){
                min = dp[n-1][j];
            }
        }
        
        return min;
    }
}