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778-SwimInRisingWater.js
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778-SwimInRisingWater.js
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var swimInWater = function (grid) {
const n = grid.length;
let left = 0,
right = n * n - 1;
while (left < right) {
const mid = Math.floor((left + right) / 2);
if (check(grid, mid)) {
right = mid;
} else {
left = mid + 1;
}
}
return left;
};
const check = (grid, threshold) => {
if (grid[0][0] > threshold) {
return false;
}
const n = grid.length;
const visited = new Array(n).fill(0).map(() => new Array(n).fill(false));
visited[0][0] = true;
const queue = [[0, 0]];
const directions = [
[0, 1],
[0, -1],
[1, 0],
[-1, 0],
];
while (queue.length) {
const square = queue.shift();
const i = square[0],
j = square[1];
for (const direction of directions) {
const ni = i + direction[0],
nj = j + direction[1];
if (ni >= 0 && ni < n && nj >= 0 && nj < n) {
if (!visited[ni][nj] && grid[ni][nj] <= threshold) {
queue.push([ni, nj]);
visited[ni][nj] = true;
}
}
}
}
return visited[n - 1][n - 1];
};