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48 | 48 |
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49 | 49 | <p><strong>进阶:</strong>你能实现时间复杂度为 <code>O(n)</code> ,空间复杂度为 <code>O(1)</code> 的解决方案吗?</p>
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50 | 50 |
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51 |
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52 | 51 | ## 解法
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53 | 52 |
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54 | 53 | <!-- 这里可写通用的实现逻辑 -->
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55 | 54 |
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| 55 | +用 min, mid 记录遍历过程中遇到的最小值以及中间值,若出现 num > mid,说明找到了满足题目的三元组,返回 true;否则遍历结束返回 false。 |
| 56 | + |
56 | 57 | <!-- tabs:start -->
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57 | 58 |
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58 | 59 | ### **Python3**
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59 | 60 |
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60 | 61 | <!-- 这里可写当前语言的特殊实现逻辑 -->
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61 | 62 |
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62 | 63 | ```python
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63 |
| - |
| 64 | +class Solution: |
| 65 | + def increasingTriplet(self, nums: List[int]) -> bool: |
| 66 | + mi, mid = float('inf'), float('inf') |
| 67 | + for num in nums: |
| 68 | + if num > mid: |
| 69 | + return True |
| 70 | + if num <= mi: |
| 71 | + mi = num |
| 72 | + else: |
| 73 | + mid = num |
| 74 | + return False |
64 | 75 | ```
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65 | 76 |
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66 | 77 | ### **Java**
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67 | 78 |
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68 | 79 | <!-- 这里可写当前语言的特殊实现逻辑 -->
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69 | 80 |
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70 | 81 | ```java
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| 82 | +class Solution { |
| 83 | + public boolean increasingTriplet(int[] nums) { |
| 84 | + int n = nums.length; |
| 85 | + int[] lmi = new int[n]; |
| 86 | + int[] rmx = new int[n]; |
| 87 | + lmi[0] = Integer.MAX_VALUE; |
| 88 | + rmx[n - 1] = Integer.MIN_VALUE; |
| 89 | + for (int i = 1; i < n; ++i) { |
| 90 | + lmi[i] = Math.min(lmi[i - 1], nums[i - 1]); |
| 91 | + } |
| 92 | + for (int i = n - 2; i >= 0; --i) { |
| 93 | + rmx[i] = Math.max(rmx[i + 1], nums[i + 1]); |
| 94 | + } |
| 95 | + for (int i = 0; i < n; ++i) { |
| 96 | + if (lmi[i] < nums[i] && nums[i] < rmx[i]) { |
| 97 | + return true; |
| 98 | + } |
| 99 | + } |
| 100 | + return false; |
| 101 | + } |
| 102 | +} |
| 103 | +``` |
| 104 | + |
| 105 | +空间优化: |
| 106 | + |
| 107 | +```java |
| 108 | +class Solution { |
| 109 | + public boolean increasingTriplet(int[] nums) { |
| 110 | + int min = Integer.MAX_VALUE, mid = Integer.MAX_VALUE; |
| 111 | + for (int num : nums) { |
| 112 | + if (num > mid) { |
| 113 | + return true; |
| 114 | + } |
| 115 | + if (num <= min) { |
| 116 | + min = num; |
| 117 | + } else { |
| 118 | + mid = num; |
| 119 | + } |
| 120 | + } |
| 121 | + return false; |
| 122 | + } |
| 123 | +} |
| 124 | +``` |
| 125 | + |
| 126 | +### **C++** |
| 127 | + |
| 128 | +```cpp |
| 129 | +class Solution { |
| 130 | +public: |
| 131 | + bool increasingTriplet(vector<int>& nums) { |
| 132 | + int mi = INT_MAX, mid = INT_MAX; |
| 133 | + for (int num : nums) |
| 134 | + { |
| 135 | + if (num > mid) return true; |
| 136 | + if (num <= mi) mi = num; |
| 137 | + else mid = num; |
| 138 | + } |
| 139 | + return false; |
| 140 | + } |
| 141 | +}; |
| 142 | +``` |
71 | 143 |
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| 144 | +### **Go** |
| 145 | +
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| 146 | +```go |
| 147 | +func increasingTriplet(nums []int) bool { |
| 148 | + min, mid := math.MaxInt32, math.MaxInt32 |
| 149 | + for _, num := range nums { |
| 150 | + if num > mid { |
| 151 | + return true |
| 152 | + } |
| 153 | + if num <= min { |
| 154 | + min = num |
| 155 | + } else { |
| 156 | + mid = num |
| 157 | + } |
| 158 | + } |
| 159 | + return false |
| 160 | +} |
72 | 161 | ```
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73 | 162 |
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74 | 163 | ### **...**
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