739 每日温度
func dailyTemperatures(temperatures []int) []int {// 双指针var res = make([]int, len(temperatures))for i:=0; i<len(temperatures); i++ {for j:=i+1; j<len(temperatures); j++ {if temperatures[j] > temperatures[i] {res[i] = j - ibreak}}}return res
}// 时间n^2, 空间n 超时
//leetcode submit region begin(Prohibit modification and deletion)
func dailyTemperatures(temperatures []int) []int {// 单调栈if len(temperatures) == 1{return []int{0}}var res = make([]int, len(temperatures))var topidx intstack := list.New()for i:=0; i<len(temperatures); i++ {if stack.Len() == 0 {stack.PushFront(i)continue}topidx = stack.Front().Value.(int)if temperatures[i] <= temperatures[topidx] {stack.PushFront(i)}else {for temperatures[topidx] < temperatures[i]{idx := stack.Remove(stack.Front()).(int)res[idx] = i - idxif stack.Len() > 0 {topidx = stack.Front().Value.(int)}else {break}}stack.PushFront(i)}}return res
}
// 简洁版本
func dailyTemperatures(temperatures []int) []int {// 单调栈n := len(temperatures)res := make([]int, n)stack := []int{} // 使用切片作为栈for i := 0; i < n; i++ {for len(stack) > 0 && temperatures[i] > temperatures[stack[len(stack)-1]] {idx := stack[len(stack)-1]stack = stack[:len(stack)-1] // 弹出栈顶元素res[idx] = i - idx}stack = append(stack, i) // 压栈}return res
}
496 下一个更大元素
func nextGreaterElement(nums1 []int, nums2 []int) []int {// 两种思路，第一双循环暴力解法，第二可以单调栈求nums2每一个元素的更大元素，然后hash表nums1，得出结果var res = make([]int, len(nums1))var hash = make(map[int]int, len(nums1))for idx, num := range nums1 {hash[num] = idx}var stack = make([]int, len(nums2))var res2 = make([]int, len(nums2))for i:=0; i<len(nums2); i++{for len(stack) > 0 && nums2[i] > nums2[stack[0]] {idx := stack[0]stack = stack[1: ]res2[idx] = nums2[i]}stack = append([]int{i}, stack...)}//fmt.Println(res2)for i, v := range res2 {if idx, ok := hash[nums2[i]]; ok {if v == 0 {res[idx] = -1}else {res[idx] = v}}}return res
}
503 下一个更大元素II
func nextGreaterElements(nums []int) []int {// 思路取巧一下循环，将其变成两个数组叠加var newNums []int // 两个数组newNums = append(newNums, nums...)newNums = append(newNums, nums...)fmt.Println(newNums)var stack = make([]int, len(newNums))var res = make([]int, len(newNums))for i, _ := range res { // 初始化为-1res[i] = -1}for i:=0; i<len(newNums); i++{for len(stack) > 0 && newNums[i] > newNums[stack[len(stack) - 1]] {idx := stack[len(stack) - 1]stack = stack[ : len(stack) - 1]res[idx] = newNums[i]}stack = append(stack, i)}//fmt.Println(res)return res[ : len(nums)]
}
func nextGreaterElements(nums []int) []int {// 正常思路，涉及到环，通过取模运算实现正确的循环var stack = make([]int, len(nums))var res = make([]int, len(nums))for i, _ := range res { // 初始化为-1res[i] = -1}length := len(nums)for i:=0; i<length * 2; i++{for len(stack) > 0 && nums[i % length] > nums[stack[len(stack) - 1]] {idx := stack[len(stack) - 1]stack = stack[ : len(stack) - 1]res[idx] = nums[i % length]}stack = append(stack, i % length)}//fmt.Println(res)return res
}
