Create longest-line-of-consecutive-one-in-matrix.cpp

Author: kamyu104

C++/longest-line-of-consecutive-one-in-matrix.cpp

@@ -0,0 +1,26 @@
+// Time:  O(m * n)
+// Space: O(n)
+
+class Solution {
+public:
+    int longestLine(vector<vector<int>>& M) {
+        if (M.empty()) {
+            return 0;
+        }
+        int result = 0;
+        vector<vector<vector<int>>> dp(2, vector<vector<int>>(M[0].size(), vector<int>(4)));
+        for (int i = 0; i < M.size(); ++i) {
+            for (int j = 0; j < M[0].size(); ++j) {
+                dp[i % 2][j][0] = dp[i % 2][j][1] = dp[i % 2][j][2] = dp[i % 2][j][3] = 0
+                if (M[i][j] == 1) {
+                    dp[i % 2][j][0] = j > 0 ? dp[i % 2][j - 1][0] + 1 : 1;
+                    dp[i % 2][j][1] = i > 0 ? dp[(i - 1) % 2][j][1] + 1 : 1;
+                    dp[i % 2][j][2] = (i > 0 && j > 0) ? dp[(i - 1) % 2][j - 1][2] + 1 : 1;
+                    dp[i % 2][j][3] = (i > 0 && j < M[0].size() - 1) ? dp[(i - 1) % 2][j + 1][3] + 1 : 1;
+                    result = max(result, max(dp[i % 2][j][0], max(dp[i % 2][j][1], max(dp[i % 2][j][2], dp[i % 2][j][3]))));
+                }
+            }
+        }
+        return result;
+    }
+};