Create largest_zero_subMatrix.cpp

Author: alirezakhm

handy-algorithms/largest_zero_subMatrix.cpp

@@ -0,0 +1,25 @@
+int zero_matrix(vvi a) { // O(N * M)
+ int n = a.size(), m = a[0].size(), ans = 0;
+ vi d(m, -1), d1(m), d2(m), st;
+
+ forn(i, n) {
+ forn(j, m) if (a[i][j] == 1) d[j] = i;
+
+ forn(j, m) {
+ while (st.size() && d[st.back()] <= d[j]) st.pop_back();
+ d1[j] = st.empty() ? -1 : st.back();
+ st.push_back(j);
+ }
+ st.clear();
+
+ for (int j = m - 1; j >= 0; --j) {
+ while (st.size() && d[st.back()] <= d[j]) st.pop_back();
+ d2[j] = st.empty() ? m : st.back();
+ st.push_back(j);
+ }
+ st.clear();
+
+ forn(j, m) ans = max(ans, (i - d[j]) * (d2[j] - d1[j] - 1)); 
+ }
+ return ans;
+}