Create 1901-find-a-peak-element-ii.js

Author: everthis

1901-find-a-peak-element-ii.js

@@ -0,0 +1,28 @@
+/**
+ * @param {number[][]} mat
+ * @return {number[]}
+ */
+const findPeakGrid = function(mat) {
+    let lowCol = 0;
+    let highCol = mat[0].length - 1;
+
+    while(lowCol <= highCol) {
+        let midCol = lowCol + ~~((highCol - lowCol) / 2);
+        let maxRow = 0;
+        for(let i = 0; i < mat.length; i++) {
+            maxRow = mat[i][midCol] > mat[maxRow][midCol] ? i : maxRow;
+        }
+
+        let isLeftElementBig = midCol - 1 >= lowCol && mat[maxRow][midCol - 1] > mat[maxRow][midCol];
+        let isRightElementBig = midCol + 1 <= highCol && mat[maxRow][midCol + 1] > mat[maxRow][midCol];
+
+        if(!isLeftElementBig && !isRightElementBig) {
+            return [maxRow, midCol];
+        } else if(isRightElementBig) {
+            lowCol = midCol + 1;
+        } else {
+            highCol = midCol - 1;
+        }
+    }
+    return null;
+};