week 5 265. Paint House II

public class Solution {
public int minCostII(int[][] costs) {
    if(costs == null || costs.length == 0 || costs[0].length == 0) {
          return 0;
    }
      
    
    int n = costs.length;
    int k = costs[0].length;
    
    if(k == 1){ 
        return (n==1? costs[0][0] : -1);
    }  
    
    int prevMin = 0; 
    int prevMinInd = -1; 
    int prevSecMin = 0;
    
    for(int i = 0; i<n; i++) {
        int min = Integer.MAX_VALUE; 
        int minInd = -1; 
        int secMin = Integer.MAX_VALUE;
        for(int j = 0; j<k;  j++) {
            int val = costs[i][j] + (j == prevMinInd ? prevSecMin : prevMin);
            if(minInd < 0) {
                min = val; 
                minInd = j;
            }else if(val < min) { 
                secMin = min;
                min = val;
                minInd = j;
            } else if(val < secMin) { 
                secMin = val;
            }
        }
        prevMin = min;
        prevMinInd = minInd;
        prevSecMin = secMin;
    }
    return prevMin;
   }
}