Runtime: 317 ms (Top 73.49%) | Memory: 75.60 MB (Top 73.49%)

Author: AnasImloul

scripts/algorithms/R/Range Sum Query 2D Immutable/Range Sum Query 2D Immutable.js

@@ -0,0 +1,47 @@
+// Runtime: 317 ms (Top 73.49%) | Memory: 75.60 MB (Top 73.49%)
+
+var NumMatrix = function(matrix) {
+
+    let R = matrix.length
+    let C = matrix[0].length
+
+    this.sumMatrix = Array.from({length: R + 1}, () => new Array(C + 1).fill(0))
+
+    for (let r = 0; r < R; r++) {
+
+        let prefix = 0
+
+        for (let c = 0; c < C; c++) {
+
+            prefix += matrix[r][c]
+
+            let above = this.sumMatrix[r][c + 1]
+
+            this.sumMatrix[r + 1][c + 1] = prefix + above
+        }
+
+    }
+    
+};
+
+NumMatrix.prototype.sumRegion = function(row1, col1, row2, col2) {
+
+    row1 = row1 + 1
+    col1 = col1 + 1
+    row2 = row2 + 1
+    col2 = col2 + 1
+
+    let bottomRight = this.sumMatrix[row2][col2]
+    let above = this.sumMatrix[row1 - 1][col2]
+    let left = this.sumMatrix[row2][col1 - 1]
+    let topLeft = this.sumMatrix[row1 - 1][col1 - 1]
+
+    return bottomRight - above - left + topLeft
+    
+};
+
+/** 
+ * Your NumMatrix object will be instantiated and called as such:
+ * var obj = new NumMatrix(matrix)
+ * var param_1 = obj.sumRegion(row1,col1,row2,col2)
+ */