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阿华代码，不是逆风，就是我疯
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目录
第一题：移动零
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class Solution { public void moveZeroes(int[] nums) { int dest = -1; int cur = 0; int tem = 0; while(cur < nums.length){ if(nums[cur] != 0){ dest++; tem = nums[dest] ; nums[dest] = nums[cur]; nums[cur] = tem; } cur++; } } }
第二题：复写零
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class Solution { public void duplicateZeros(int[] arr) { int cur = 0 , dest = -1 , n = arr.length; while(cur <= n){//dest位置不确定所以不能用作判断循环的条件 if(arr[cur] != 0){ dest++; }else{ dest += 2; } if(dest >= n-1){ break; } cur++; } if(dest == n){ arr[n-1] = 0; dest -= 2; cur--; } //开始从后往前复写 while(cur >= 0 ){ if(arr[cur] != 0){ arr[dest] = arr[cur]; cur--; dest--; }else{ arr[dest] = arr[cur]; dest--; arr[dest] = arr[cur]; cur--; dest--; } } } }
第三题：快乐数
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class Solution { public static int sumResult(int n){ int sum = 0; while(n != 0){ //int tem = n % 10; //sum += tem * tem; sum += Math.pow(n%10,2); n = n/10; } return sum; } public boolean isHappy(int n) { int slow = n ,fast = sumResult(n); while(slow != fast){ slow = sumResult(slow); fast = sumResult(sumResult(fast)); } return slow == 1; } }
第四题：盛最多水的容器
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class Solution { public int maxArea(int[] height) { int left = 0 ,right = height.length -1 , ret = 0; while(left < right){ int v = Math.min(height[left],height[right]) * (right - left); ret = Math.max(ret,v); if(height[left] < height[right]){ left++; }else{ right--; } } return ret; } }
第五题：有效三角形的个数
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class Solution { public int triangleNumber(int[] nums) { int end = nums.length-1; Arrays.sort(nums); int count = 0; for( ; end >= 2 ; end--){ int right = end-1; int left = 0; while(left < right){ int tem = nums[left] + nums[right]; if(tem > nums[end]){ count += right - left; right--; }else{ left++; } } } return count; } }
第六题：和为s的两个数
LCR 179. 查找总价格为目标值的两个商品 - 力扣（LeetCode）
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class Solution6 { public int[] twoSum(int[] price, int target) { int n = price.length; int left = 0 , right = n-1; int[] car = {-1,-1}; while(left < right){ int result = sum(price[left],price[right]); if(result < target){ left++; }else if(result > target){ right--; }else{ car[0] = price[left]; car[1] = price[right]; return car; } } return car; } public int sum(int a , int b){ int sum = a + b; return sum; } }
第七题：三数之和
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class Solution { public List<List<Integer>> threeSum(int[] nums) { Arrays.sort(nums); int n = nums.length; List<List<Integer>> ret = new ArrayList<>(); for(int i = 0 ; i < n ;){ if(nums[i] > 0){ break; } int left = i+1 , right = n-1 ,target = -nums[i]; while(left < right){ int sum = sum(nums[left] , nums[right]); if(sum > target){ right--; }else if(sum < target){ left++; }else{ ret.add(Arrays.asList(nums[left] , nums[right] , nums[i])); left++; right--; while(left < right && nums[left] == nums[left - 1]){ left++; } while(left < right && nums[right] == nums[right + 1]){ right--; } } } i++; while(i < n && nums[i] == nums[i-1]){ i++; } } return ret; } public int sum(int a , int b){ return a+b; } }
第八题：四数之和
强烈建议先把三数之和看完
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class Solution { public List<List<Integer>> fourSum(int[] nums, int target) { List<List<Integer>> list = new ArrayList(); Arrays.sort(nums); int n = nums.length; for(int i = 0 ; i < n ; ){ //第一层循环遍历固定a遍历数组 int a = nums[i]; for(int j = i+1 ; j < n ; ){ int b = nums[j] , left = j+1 ,right = n-1; long tem = (long)target - a - b; while(left < right){ long sum = sum(nums[left],nums[right]); if(sum > tem){ right--; }else if(sum < tem){ left++; }else{ list.add(Arrays.asList(a,b,nums[left],nums[right])); left++; right--; while(left < right && nums[left] == nums[left-1]){ left++; } while(right > left && nums[right] == nums[right+1]){ right--; } } } j++; while(j < n-2 && nums[j] == nums[j-1]){ j++; } } i++; while(i < n-1 && nums[i] == nums[i-1]){ i++; } } return list; } public int sum(int a , int b){ return a+b; } }
