Create 1594-maximum-non-negative-product-in-a-matrix.js

Author: everthis

1594-maximum-non-negative-product-in-a-matrix.js

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+/**
+ * @param {number[][]} grid
+ * @return {number}
+ */
+const maxProductPath = function (grid) {
+  const m = grid.length,
+    n = grid[0].length,
+    MOD = 1e9 + 7;
+  const mx = Array.from({ length: m }, () => Array(n).fill(0));
+  const mn = Array.from({ length: m }, () => Array(n).fill(0));
+  mx[0][0] = mn[0][0] = grid[0][0];
+
+  // initialize the top and left sides
+  for (let i = 1; i < m; i++) {
+    mn[i][0] = mx[i][0] = mx[i - 1][0] * grid[i][0];
+  }
+  for (let j = 1; j < n; j++) {
+    mn[0][j] = mx[0][j] = mx[0][j - 1] * grid[0][j];
+  }
+
+  for (let i = 1; i < m; i++) {
+    for (let j = 1; j < n; j++) {
+      if (grid[i][j] < 0) {
+        // smallest negative * negative number = largest
+        mx[i][j] = Math.min(mn[i - 1][j], mn[i][j - 1]) * grid[i][j];
+        mn[i][j] = Math.max(mx[i - 1][j], mx[i][j - 1]) * grid[i][j];
+      } else {
+        // largest product * positive number = largest
+        mx[i][j] = Math.max(mx[i - 1][j], mx[i][j - 1]) * grid[i][j];
+        mn[i][j] = Math.min(mn[i - 1][j], mn[i][j - 1]) * grid[i][j];
+      }
+    }
+  }
+
+  let ans = mx[m - 1][n - 1] % MOD;
+  return ans < 0 ? -1 : ans;
+};