Add solution #1074

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,114 LeetCode solutions in JavaScript
+# 1,115 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -854,6 +854,7 @@
 1071|[Greatest Common Divisor of Strings](./solutions/1071-greatest-common-divisor-of-strings.js)|Easy|
 1072|[Flip Columns For Maximum Number of Equal Rows](./solutions/1072-flip-columns-for-maximum-number-of-equal-rows.js)|Medium|
 1073|[Adding Two Negabinary Numbers](./solutions/1073-adding-two-negabinary-numbers.js)|Medium|
+1074|[Number of Submatrices That Sum to Target](./solutions/1074-number-of-submatrices-that-sum-to-target.js)|Hard|
 1079|[Letter Tile Possibilities](./solutions/1079-letter-tile-possibilities.js)|Medium|
 1081|[Smallest Subsequence of Distinct Characters](./solutions/1081-smallest-subsequence-of-distinct-characters.js)|Medium|
 1092|[Shortest Common Supersequence](./solutions/1092-shortest-common-supersequence.js)|Hard|

solutions/1074-number-of-submatrices-that-sum-to-target.js

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+/**
+ * 1074. Number of Submatrices That Sum to Target
+ * https://leetcode.com/problems/number-of-submatrices-that-sum-to-target/
+ * Difficulty: Hard
+ *
+ * Given a matrix and a target, return the number of non-empty submatrices that sum to target.
+ *
+ * A submatrix x1, y1, x2, y2 is the set of all cells matrix[x][y] with x1 <= x <= x2 and
+ * y1 <= y <= y2.
+ *
+ * Two submatrices (x1, y1, x2, y2) and (x1', y1', x2', y2') are different if they have some
+ * coordinate that is different: for example, if x1 != x1'.
+ */
+
+/**
+ * @param {number[][]} matrix
+ * @param {number} target
+ * @return {number}
+ */
+var numSubmatrixSumTarget = function(matrix, target) {
+  const rows = matrix.length;
+  const cols = matrix[0].length;
+  let result = 0;
+
+  for (let i = 0; i < rows; i++) {
+    const prefixSums = new Array(cols).fill(0);
+    for (let j = i; j < rows; j++) {
+      const sumFreq = new Map([[0, 1]]);
+      let currentSum = 0;
+
+      for (let k = 0; k < cols; k++) {
+        prefixSums[k] += matrix[j][k];
+        currentSum += prefixSums[k];
+        result += sumFreq.get(currentSum - target) || 0;
+        sumFreq.set(currentSum, (sumFreq.get(currentSum) || 0) + 1);
+      }
+    }
+  }
+
+  return result;
+};