数组-长度最小的子数组

M长度最小的子数组（leetcode209）

/*** @param {number} target* @param {number[]} nums* @return {number}*/
var minSubArrayLen = function(target, nums) {const n = nums.length;let ans = n + 1;let sum = 0;    //  子数组元素和let left = 0;   //  子数组左端点for (let right = 0; right < n; right++) {   //  枚举子数组右端点sum += nums[right];while (sum - nums[left] >= target) {    // 尽量缩小子数组长度sum -= nums[left++]; // 左端点右移}if (sum >= target) {ans = Math.min(ans, right - left + 1);}}return ans <= n ? ans : 0;
};

水果成篮（leetcode094）

/*** @param {number[]} fruits* @return {number}*/
var totalFruit = function(fruits) {const n = fruits.length;const cnt = new Map();let left = 0, ans = 0;for (let right = 0; right < n; ++right) {cnt.set(fruits[right],(cnt.get(fruits[right]) || 0) + 1);while (cnt.size > 2) {cnt.set(fruits[left], cnt.get(fruits[left]) - 1);if (cnt.get(fruits[left]) == 0) {cnt.delete(fruits[left]);}++left;}ans = Math.max(ans , right - left + 1);}return ans;
};

H最小覆盖子串（leetcode76）

/*** @param {string} s* @param {string} t* @return {string}*/
var minWindow = function(s, t) {let minLen = s.length + 1;let start = s.length;let map = {};let missingType = 0;for (const c of t) {if (!map[c]) {missingType++;map[c] = 1;} else {map[c]++;}}let l = 0, r = 0;for (; r < s.length; r++) {let rightChar = s[r];if (map[rightChar] !== undefined) map[rightChar]--;if (map[rightChar] == 0) missingType--;while (missingType == 0) {if (r - l + 1 < minLen) {minLen = r - l + 1;start = l;}let leftChar = s[l];if (map[leftChar] !== undefined) map[leftChar]++;if (map[leftChar] > 0) missingType++;l++;}}if (start == s.length) return "";return s.substring(start, start + minLen);
};