https://leetcode.cn/problems/4sum/submissions/589840312/
三数之和硬改过来的
```js
var fourSum = function (nums, target) {
nums = nums.sort((a, b) => a - b)
const result = [];
const cache = new Map()
for (let top = 0; top < nums.length; top++) {
const t = nums;
for (let index = top + 1; index < nums.length; index++) {
const a = nums;
let indey = index + 1;
let indez = nums.length - 1
while (indey < nums.length && indez != index && indey < indez) {
const b = nums
const c = nums
const num = a + b + c + t
if (num === target) {
const tag = .join(' ')
if (cache.has(tag)) {
indey++;
} else {
result.push()
indey++;
indez--;
cache.set(tag, true);
}
} else if (num - target < 0) {
indey++;
} else {
indez--;
}
}
}
}
return result
};
```
https://leetcode.cn/problems/3sum-closest/submissions/589851344/
写错个0以为自己算法错了
扣了半个小时我日
```js
var threeSumClosest = function (nums, target) {
nums = nums.sort((a, b) => a - b)
let sep = Number.MAX_SAFE_INTEGER;
let ans = 0
for (let index = 0; index < nums.length; index++) {
const a = nums;
let indey = index + 1;
let indez = nums.length - 1
while (indey < nums.length && indez != index && indey < indez) {
const b = nums
const c = nums
const num = a + b + c
if (num === target) {
indey++;
} else if (num < target) {
indey++;
} else {
indez--;
}
if (Math.abs(target - num) < sep) {
sep=Math.abs(target - num)
ans = num
}
}
}
return ans
};
```
https://leetcode.cn/problems/rank-teams-by-votes/
打卡题
```js
var rankTeams = function (votes) {
const rank = new Array(26).fill(0).map((val, index) => {
return {
char: index,
arr: new Array(votes.length).fill(0),
};
});
for (let index = 0; index < votes.length; index++) {
for (let indey = 0; indey < votes.length; indey++) {
const char = votes;
rank.arr++;
}
}
rank.sort((a, b) => {
for (let index = 0; index < a.arr.length; index++) {
const num1 = a.arr;
const num2 = b.arr;
if (num1 > num2) {
return -1;
}
if (num1 < num2) {
return 1;
}
}
return a.char - b.char;
});
let ans = "";
for (let index = 0; index < votes.length; index++) {
ans+=String.fromCharCode(rank.char+65)
}
return ans
};
```
https://leetcode.cn/problems/linked-list-in-binary-tree/
打卡题
```js
var isSubPath = function (head, root) {
const dfs = (root1, root2) => {
if (root2 == null) {
return true;
}
if (root1 == null) {
return false;
}
let ans = false;
if (root1.val == root2.val) {
ans = dfs(root1.left, root2.next) || dfs(root1.right, root2.next);
}
ans = ans || (root2==head&&(dfs(root1.left, head) || dfs(root1.right, head)));
return ans;
};
return dfs(root, head);
};
```
https://leetcode.cn/problems/subtree-of-another-tree/submissions/590282320/
这题是简单？
```js
var isSubtree = function (root, subRoot) {
const dfs = (root1, root2) => {
if (root2 == null&&root1 == null) {
return true;
}
if (root1 == null) {
return false;
}
if (root2 == null) {
return false;
}
let ans = false;
if (root1.val == root2.val) {
ans = dfs(root1.left, root2.left) && dfs(root1.right, root2.right);
}
ans =
ans ||
(root2 == subRoot && (dfs(root1.left, subRoot)||dfs(root1.right, subRoot)));
return ans;
};
return dfs(root,subRoot)
};
```
https://leetcode.cn/problems/divide-two-integers/submissions/590288371/
二分法秒了
```js
var divide = function (dividend, divisor) {
const symbol =
(divisor < 0 && dividend > 0) || (divisor > 0 && dividend < 0) ? -1 : 1;
divisor = Math.abs(divisor) ;
dividend = Math.abs(dividend) ;
let l = 0;
let r = dividend;
let ans = 0;
while (l <= r) {
const center = l + Math.floor((r - l) / 2);
if (center * divisor > dividend) {
r = center - 1;
} else {
l = center + 1;
ans = center;
}
}
ans=ans * symbol
if(ans> 2147483647){
return 2147483647
}
if(ans< -2147483648){
return-2147483648
}
return ans ;
};
```
https://leetcode.cn/problems/minimum-cost-for-cutting-cake-ii/submissions/590434597/
贪心法直接打过了
```js
var minimumCost = function (m, n, horizontalCut, verticalCut) {
horizontalCut.sort((a, b) => b - a);
verticalCut.sort((a, b) => b - a);
h = 0;
v = 0;
vBlock = 1;
hBlock = 1;
ans = 0
while (h < horizontalCut.length && v < verticalCut.length) {
if (horizontalCut > verticalCut) {
hBlock++;
ans += horizontalCut * vBlock
h++
} else {
vBlock++;
ans += verticalCut * hBlock
v++
}
}
while (h < horizontalCut.length) {
hBlock++;
ans += horizontalCut * vBlock
h++
}
while (v < verticalCut.length) {
vBlock++;
ans += verticalCut * hBlock
v++
}
return ans
};
```
https://leetcode.cn/problems/combination-sum-ii/submissions/590446003/
dfs按数组跑下去被卡时间了
转换结构一下就过了
```js
var combinationSum2 = function (candidates, target) {
const map = new Map();
for (let index = 0; index < candidates.length; index++) {
const candidate = candidates;
map.set(candidate, (map.get(candidate) ?? 0) + 1);
}
candidates = [...map.keys()];
candidates.sort((a, b) => a - b);
const ans = [];
const dfs = (pos, val, arr) => {
if (val > target) {
return;
}
if (val == target) {
ans.push([...arr]);
return;
}
if (pos >= candidates.length) {
return;
}
dfs(pos + 1, val, arr);
let maxCount = map.get(candidates);
const newArr = [...arr];
for (let index = 1; index <= maxCount; index++) {
newArr.push(candidates);
dfs(pos + 1, val + candidates * index, newArr);
}
};
dfs(0, 0, []);
return ans;
};
```
https://leetcode.cn/problems/count-and-say/submissions/590452129/
递归问题，还挺简单的，写的也很爽，有思路，好题！
```js
var countAndSay = function (n) {
const dfs = (i) => {
if (i == 1) {
return "1";
}
const last = dfs(i - 1);
let ans = "";
for (let index = 0; index < last.length; index++) {
const char = last;
let end = index;
while (last == char) {
end++;
}
ans += `${end - index+1}${char}`;
index = end;
}
return ans
};
return dfs(n)
};
```
https://leetcode.cn/problems/sudoku-solver/submissions/590541196/
dfs炸了
```js
var solveSudoku = function (board) {
const next = (x, y) => {
if (y >= board.length) {
return ;
} else {
return ;
}
};
const line = new Array(9).fill(0).map(() => new Map());
const row = new Array(9).fill(0).map(() => new Map());
const block = new Array(9).fill(0).map(() => new Map());
const setChar = (index, indey, char, status = true) => {
line.set(char, status);
row.set(char, status);
block.set(char, status);
};
const getUseNumber = (x, y) => {
const list = [];
for (let index = 1; index <= 9; index++) {
const num = index + "";
if (line.get(num) == true) {
continue;
}
if (row.get(num) == true) {
continue;
}
if (block.get(num) == true) {
continue;
}
list.push(num);
}
return list;
};
let ans = false;
const dfs = (x, y) => {
if (x == board.length) {
ans = true;
return;
}
const char = board;
if (char == ".") {
const list = getUseNumber(x, y);
const = next(x, y);
for (let index = 0; index < list.length; index++) {
const num = list;
board = num;
setChar(x, y, num);
dfs(nextX, nextY);
if (ans == true) {
break;
}
setChar(x, y, num, false);
board = ".";
}
} else {
const = next(x, y);
dfs(nextX, nextY);
}
};
for (let index = 0; index < board.length; index++) {
for (let indey = 0; indey < board.length; indey++) {
const char = board;
if (char == ".") {
continue;
}
setChar(index, indey, char);
}
}
dfs(0, 0);
};
```