let twoSumLessThanK = function(A, K) {
let max = -1, start = 0, end = A.length - 1;
A.sort((a, b) => b - a); //?
while (start < end) {
let sum = A[start] + A[end];
if (sum < K) {
max = Math.max(sum, max);
end--;
}
else {
start++;
}
}
return max;
};
Category: Loop
if (!grid || !grid.length) return 0;
let numRows = grid.length,
numCols = grid[0].length,
LAND = 1, VISITED = 2;
function markAndVisit(row, col, island = [], level = 0) {
if (grid[row][col] === LAND) {
grid[row][col] = VISITED;
island.push('X' + level);
// up
if (row > 0 && grid[row - 1][col] === LAND) {
island.push('U' + level);
markAndVisit(row - 1, col, island, level + 1);
}
// down
if (row < numRows - 1 && grid[row + 1][col] === LAND) {
island.push('D' + level);
markAndVisit(row + 1, col, island, level + 1);
}
// left
if (col > 0 && grid[row][col - 1] === LAND) {
island.push('L' + level);
markAndVisit(row, col - 1, island, level + 1);
}
// right
if (col < numCols - 1 && grid && grid[row][col + 1] === LAND) {
island.push('R' + level);
markAndVisit(row, col + 1, island, level + 1);
}
}
return island;
}
let islands = new Set();
for (let row = 0; row < numRows;row++) {
for (let col = 0; col < numCols;col++) {
if (grid[row][col] === LAND) {
let island = markAndVisit(row, col);
// console.log(island);
if (island.length) islands.add(island.join(''));
}
}
}
// console.table(grid);
return islands.size;
let reorganizeString = function(S) {
let chars = {}, max = 0;
for(let i = 0; i < S.length;i++) {
if (chars[S[i]]) {
chars[S[i]] = chars[S[i]] + 1;
max = Math.max(chars[S[i]], max);
}
else {
chars[S[i]] = 1;
}
}
console.log(max, Math.floor((S.length + 1) / 2));
if (max > (S.length + 1) / 2) {
return "";
}
let result = [], index = 0;
const keys = Object.keys(chars).sort((a, b) => chars[b] - chars[a]); //?
while (keys.length) { //?
const key = keys.shift(); //?
result[index] = key;
if (chars[key] - 1 > 0) {
chars[key] = chars[key] - 1;
keys.unshift(key); //?
}
index += 2; //?
if (index >= S.length) {
index = 1;
}
}
return result.join('');
};
let prisonAfterNDays = function(cells, N) {
let cache = {},
counter = 1,
cycle = false,
len = 8;
let dup = [...cells];
function getNextCycle(data) {
let lastCycle = data[1];
let cycleDays = counter - lastCycle;
console.log(lastCycle, cycleDays);
let nextCycle = N - ((N - lastCycle) % cycleDays); //?.
// let nextCycle = counter; //?
// while (nextCycle + counter < N) {
// nextCycle = nextCycle += cycleDays;
// }
return nextCycle; //?
}
while(counter <= N) {
let key = dup.join(''),
data = cache[key],
row = [];
if (data && !cycle) {
cycle = true;
counter = getNextCycle(data);
}
if (data) {
dup = data[0];
counter++; //?
}
else {
for (let i = 0; i < len; i++) {
row[i] = dup[i - 1] === dup[i + 1] ? 1 : 0;
}
cache[key] = [[...row], counter];
dup = cache[key][0];
counter++; //?
}
}
return dup;
};
let mostVisitedPattern = function(username, timestamp, website) {
let map = new Map();
for (let i = 0; i < username.length; i++) {
if (map.has(username[i])) {
map.get(username[i]).push([website[i], timestamp[i]]);
}
else {
map.set(username[i], [[website[i], timestamp[i]]]);
}
}
// get all possibilites
let visitedPattern = {};
let possibilityMap = new Map();
for(let [user, visits] of map.entries()) {
visitedPattern[user] = {};
const value = visits.sort((a, b) => a[1] - b[1]).map(([a]) => a);
if ( value.length < 3) continue;
for (let i = 0; i < value.length - 2; i++) {
for (let j = i + 1; j < value.length - 1; j++) {
for (let k = j + 1; k < value.length; k++) {
let key = `${value[i]},${value[j]},${value[k]}`;
if(possibilityMap.has(key)) {
if(!visitedPattern[user][key]) {
possibilityMap.set(key, possibilityMap.get(key) + 1);
visitedPattern[user][key] = 1;
}
}
else {
possibilityMap.set(key, 1);
visitedPattern[user][key] = 1;
}
}
}
}
}
const result = [...possibilityMap];
return result.sort((a, b) => {
if(a[1] < b[1]) {
return 1;
}
else if (a[1] > b[1]) {
return -1;
}
return a[0].localeCompare(b[0]);
}).map(arr => arr[0]).shift().split(','); //?
// result.pop(); //?
// .map(arr => arr[0]).pop().split('|'); //?
};