Update find-a-good-subset-of-the-matrix.cpp

Author: kamyu104

C++/find-a-good-subset-of-the-matrix.cpp

@@ -14,38 +14,9 @@ class Solution {
             if (!mask) {
                 return {i};
             }
-            for (int mask2 = ((1 << size(grid[0])) - 1) ^ mask, submask = mask2; submask > 0; submask = (submask - 1) & mask2) {
-                if (lookup.count(submask)) {
-                    return {lookup[submask], i};
-                }
-            }
-            lookup[mask] = i;
-        }
-        return {};
-    }
-};
-
-// Time:  O(m * 2^n)
-// Space: O(2^n)
-// bitmasks, constructive algorithms, greedy
-class Solution2 {
-public:
-    vector<int> goodSubsetofBinaryMatrix(vector<vector<int>>& grid) {
-        unordered_map<int, int> lookup;
-        for (int i = 0; i < size(grid); ++i) {
-            int mask = 0;
-            for (int j = 0; j < size(grid[0]); ++j) {
-                mask |= grid[i][j] << j;
-            }
-            if (!mask) {
-                return {i};
-            }
-            for (int mask2 = 1; mask2 < 1 << size(grid[0]); ++mask2) {
-                if (mask & mask2) {
-                    continue;
-                }
-                if (lookup.count(mask2)) {
-                    return {lookup[mask2], i};
+            for (const auto& [mask2, j] : lookup) {
+                if ((mask2 & mask) == 0) {
+                    return {j, i};
                 }
             }
             lookup[mask] = i;