Create maximum-non-negative-product-in-a-matrix.cpp

Author: kamyu104

C++/maximum-non-negative-product-in-a-matrix.cpp

@@ -0,0 +1,30 @@
+// Time:  O(m * n)
+// Space: O(n)
+
+// dp with rolling window
+class Solution {
+public:
+    int maxProductPath(vector<vector<int>>& grid) {
+        static const int MOD = 1e9 + 7;
+        vector<vector<int64_t>> max_dp(2, vector<int64_t>(size(grid[0])));
+        vector<vector<int64_t>> min_dp(2, vector<int64_t>(size(grid[0])));
+        for (int i = 0; i < size(grid); ++i) {
+            for (int j = 0; j < size(grid[0]); ++j) {
+                if (i == 0 && j == 0) {
+                    max_dp[0][0] = min_dp[0][0] = grid[0][0];
+                    continue;
+                }
+                auto curr_max = max(i > 0 ? max_dp[(i - 1) % 2][j] : max_dp[i % 2][j - 1],
+                                    j > 0 ? max_dp[i % 2][j - 1] : max_dp[(i - 1) % 2][j]);
+                auto curr_min = min(i > 0 ? min_dp[(i - 1) % 2][j] : min_dp[i % 2][j - 1],
+                                    j > 0 ? min_dp[i % 2][j - 1] : min_dp[(i - 1) % 2][j]);
+                if (grid[i][j] < 0) {
+                    swap(curr_max, curr_min);
+                }
+                max_dp[i % 2][j] = curr_max * grid[i][j];
+                min_dp[i % 2][j] = curr_min * grid[i][j];
+            }
+        }
+        return max_dp[(size(grid) - 1) % 2].back() >= 0 ? max_dp[(size(grid) - 1) % 2].back() % MOD : -1;
+    }
+};