solve search a 2d matrix

coding_interviews/leetcode/medium/search-a-2d-matrix/search-a-2d-matrix.js

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+function getMiddle(start, end) {
+  return Math.floor((start + end) / 2);
+}
+
+function binarySearch(list, target) {
+  let start = 0;
+  let end = list.length - 1;
+  let middle = getMiddle(start, end);
+
+  while (start <= end) {
+    if (list[middle] === target) {
+      return true;
+    } else if (list[middle] > target) {
+      end = middle - 1;
+      middle = getMiddle(start, end);
+    } else {
+      start = middle + 1;
+      middle = getMiddle(start, end);
+    }
+  }
+
+  return false;
+}
+
+function searchMatrix(matrix, target) {
+  let targetRow;
+
+  for (let rowIndex = 0; rowIndex < matrix.length; rowIndex++) {
+    let rowFirstNum = matrix[rowIndex][0];
+    let rowLastNum = matrix[rowIndex][matrix[rowIndex].length - 1];
+
+    if (target >= rowFirstNum && target <= rowLastNum) {
+      targetRow = rowIndex;
+    }
+  }
+
+  return matrix[targetRow] ? binarySearch(matrix[targetRow], target) : false;
+}