maximal Rectangle
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const maximalRectangle = (matrix) => {
if (!matrix.length || !matrix[0].length) return 0;
const height = matrix.length;
const width = matrix[0].length;
const lefts = matrix[0].map(() => 0);
const rights = matrix[0].map(() => width);
const heights = lefts.slice();
let max = 0;
for (let row = 0; row < height; row++) {
let left = 0;
let right = width;
for (let i = 0; i < width; i++) {
if (matrix[row][i] === '1') {
lefts[i] = Math.max(left, lefts[i]);
heights[i]++;
} else {
lefts[i] = heights[i] = 0;
left = i + 1
}
const rightIdx = width - 1 - i;
if (matrix[row][rightIdx] === '1') {
rights[rightIdx] = Math.min(right, rights[rightIdx])
} else {
rights[rightIdx] = width;
right = rightIdx;
}
}
for (let i = 0; i < width; i++) {
max = Math.max(max,(rights[i] - lefts[i]) * heights[i]);
}
}
return max
}
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