Update 304-range-sum-query-2d-immutable.js

Author: everthis

304-range-sum-query-2d-immutable.js

@@ -40,3 +40,37 @@ NumMatrix.prototype.sumRegion = function(row1, col1, row2, col2) {
  * var obj = Object.create(NumMatrix).createNew(matrix)
  * var param_1 = obj.sumRegion(row1,col1,row2,col2)
  */
+
+// another
+
+/**
+ * @param {number[][]} matrix
+ */
+const NumMatrix = function(matrix) {
+  const m = matrix.length, n = matrix[0].length
+  const dp = Array.from({ length: m + 1 }, () => Array(n + 1).fill(0))
+  for(let i = 1; i <= m; i++) {
+    for(let j = 1; j <= n; j++) {
+      dp[i][j] = dp[i - 1][j] + dp[i][j - 1] - dp[i - 1][j - 1] + matrix[i - 1][j - 1]
+    }
+  }
+  this.dp = dp
+};
+
+/** 
+ * @param {number} row1 
+ * @param {number} col1 
+ * @param {number} row2 
+ * @param {number} col2
+ * @return {number}
+ */
+NumMatrix.prototype.sumRegion = function(row1, col1, row2, col2) {
+  const dp = this.dp
+  return dp[row2 + 1][col2 + 1] - dp[row2 + 1][col1] - dp[row1][col2 + 1] + dp[row1][col1]
+};
+
+/** 
+ * Your NumMatrix object will be instantiated and called as such:
+ * var obj = new NumMatrix(matrix)
+ * var param_1 = obj.sumRegion(row1,col1,row2,col2)
+ */