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Java Solution for LeetCode algorithm problems, continually updating
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package g1501_1600.s1504_count_submatrices_with_all_ones;
// #Medium #Array #Dynamic_Programming #Matrix #Stack #Monotonic_Stack
// #2022_04_07_Time_9_ms_(85.86%)_Space_43.1_MB_(87.32%)
public class Solution {
public int numSubmat(int[][] mat) {
int[][] dp = new int[mat.length][mat[0].length];
for (int i = 0; i < mat.length; i++) {
int c = 0;
for (int j = mat[0].length - 1; j >= 0; j--) {
if (mat[i][j] == 1) {
c++;
} else {
c = 0;
}
dp[i][j] = c;
}
}
int ans = 0;
for (int i = 0; i < mat.length; i++) {
for (int j = 0; j < mat[0].length; j++) {
int x = Integer.MAX_VALUE;
for (int k = i; k < mat.length; k++) {
x = Math.min(x, dp[k][j]);
ans += x;
}
}
}
return ans;
}
}