Create Search-a-2D-Matrix.js (ignacio-chiazzo#15)

Author: ignacio-chiazzo

LeetcodeProblems/Search-a-2D-Matrix.js

@@ -0,0 +1,87 @@
+/*
+https://leetcode.com/problems/search-a-2d-matrix/description/
+
+Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties:
+
+Integers in each row are sorted from left to right.
+The first integer of each row is greater than the last integer of the previous row.
+Example 1:
+
+Input:
+matrix = [
+  [1,   3,  5,  7],
+  [10, 11, 16, 20],
+  [23, 30, 34, 50]
+]
+target = 3
+Output: true
+Example 2:
+
+Input:
+matrix = [
+  [1,   3,  5,  7],
+  [10, 11, 16, 20],
+  [23, 30, 34, 50]
+]
+target = 13
+Output: false
+*/
+
+/**
+ * @param {number[][]} matrix
+ * @param {number} target
+ * @return {boolean}
+ */
+
+var searchMatrix = function(matrix, target) {
+  if(matrix.length === 0)
+    return false;
+  
+  var minRow = 0;
+  var maxRow = matrix.length - 1;
+  var minCol = 0
+  var maxCol = matrix[0].length - 1;
+  
+  const row = findRow(matrix, target, maxCol, minRow, maxRow);
+  const col = findColumn(matrix, target, row, minCol, maxCol);
+
+  return target === matrix[row][col];
+};
+
+var findRow = function(matrix, target, maxCol, minRow, maxRow) {
+  while(minRow < maxRow) {
+    var midRow = Math.floor((minRow + maxRow) / 2);
+    if(matrix[midRow][0] <= target && matrix[midRow][maxCol] >= target) {
+        return midRow;    
+    } if(matrix[midRow][0] < target)
+        minRow = midRow + 1;
+    else {
+        maxRow = midRow - 1;
+    }    
+  }
+
+  return minRow;
+}
+  
+var findColumn = function(matrix, target, row, minCol, maxCol) {
+  while(minCol < maxCol) {
+    const midCol = Math.floor((minCol + maxCol) / 2);
+    if(matrix[row][midCol] == target) {
+        return midCol;    
+    } else if(matrix[row][midCol] < target)
+        minCol = midCol + 1;
+    else {
+        maxCol = midCol - 1;
+    }    
+  }
+
+  return minCol;
+}
+
+var main = function(){
+  const matrix = [[1,3,5,7],[10,11,16,20],[23,30,34,50]];
+  console.log(searchMatrix(matrix, 3));
+}
+
+main();
+module.exports.main = main;