Maximal Square

Author: ignacio-chiazzo

LeetcodeProblems/Maximal_Square.js

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+/*
+221. Maximal Square
+
+https://leetcode.com/problems/maximal-square/
+
+Given a 2D binary matrix filled with 0's and 1's, find the largest square containing only 1's and return its area.
+
+Example:
+
+Input: 
+
+1 0 1 0 0
+1 0 1 1 1
+1 1 1 1 1
+1 0 0 1 0
+
+Output: 4
+*/
+
+/**
+ * @param {character[][]} matrix
+ * @return {number}
+ */
+var maximalSquare = function(matrix) {
+  var maxSquare = 0;
+  for(var i = 0; i < matrix.length; i++) {
+    for(var j = 0; j < matrix[0].length; j++) {
+      if(matrix[i][j] === "1") { // found a 1
+        const currentMaxSideLength = getCurrentMaxSideLength(matrix, i, j);
+        if(currentMaxSideLength ** 2 > maxSquare)
+            maxSquare = currentMaxSideLength ** 2;
+      }   
+    }
+  }
+  
+  return maxSquare;
+};
+
+var getCurrentMaxSideLength = function(matrix, i, j) {
+  var max = 1;
+  while(i + max < matrix.length && j + max < matrix[0].length) {
+    var lastRow = i + max;
+    var lastCol = j + max;
+        
+    // check last column
+    var iterRow = i; 
+    while(iterRow <= lastRow){
+      if(matrix[iterRow][lastCol] === "0")
+        return max;
+      
+      iterRow++;
+    }
+    
+    // check last row
+    var iterCol = j;
+    while(iterCol <= lastCol) {
+      if(matrix[lastRow][iterCol] === "0")
+        return max;
+      iterCol++;
+    }
+    
+    max++;
+  }
+  
+  return max;
+}
+
+var main = function() {
+  console.log(maximalSquare([["1","0"]]));
+  console.log(maximalSquare([["1"]]));
+  console.log(maximalSquare([["0"]]));
+  console.log(
+    maximalSquare([["1","0","1","0","0"],["1","0","1","1","1"],["1","1","1","1","1"],["1","0","0","1","0"]])
+  );
+}
+
+module.exports.main = main