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Java Solution for LeetCode algorithm problems, continually updating
package g1201_1300.s1289_minimum_falling_path_sum_ii;
// #Hard #Array #Dynamic_Programming #Matrix #2022_03_10_Time_2_ms_(99.45%)_Space_49.8_MB_(80.07%)
public class Solution {
public int minFallingPathSum(int[][] grid) {
int n = grid[0].length;
int[] prev = new int[n];
int[] curr = new int[n];
int prevMinOne = 0;
int prevMinTwo = 0;
for (int[] ints : grid) {
int currMinOne = Integer.MAX_VALUE;
int currMinTwo = Integer.MAX_VALUE;
for (int j = 0; j < n; j++) {
int prevMin = prev[j] == prevMinOne ? prevMinTwo : prevMinOne;
curr[j] = ints[j] + prevMin;
if (curr[j] < currMinOne) {
currMinTwo = currMinOne;
currMinOne = curr[j];
} else if (curr[j] < currMinTwo) {
currMinTwo = curr[j];
}
}
prevMinOne = currMinOne;
prevMinTwo = currMinTwo;
// reuse curr array, avoid new int[] in every row
int[] temp = prev;
prev = curr;
curr = temp;
}
return prevMinOne;
}
}