leetcode

Array and Two Pointer Problems

4 files changed, 67 insertions(+), 0 deletions(-)

diff --git a/ Problems/0011.cpp b/ Problems/0011.cpp

@@ -0,0 +1,16 @@

class Solution {

public:

int trap(vector<int> &height) {

int ans = 0, n = height.size(), maxi, m1, m2;

vector<int> mleft(n), mright(n);

m1 = m2 = INT_MIN;

for (int i = 0; i < n; i++) {

mleft[i] = m1 = max(m1, height[i]);

mright[n - i - 1] = m2 = max(m2, height[n - i - 1]);

}

for (int i = 1; i < n - 1; i++) ans += min(mleft[i], mright[i]) - height[i];

return ans;

}

};

diff --git a/ Problems/0015.cpp b/ Problems/0015.cpp

@@ -0,0 +1,28 @@

class Solution {

public:

vector<vector<int>> threeSum(vector<int> &num) {

sort(num.begin(), num.end());

vector<vector<int>> res;

for (int i = 0; i < num.size();) {

int target = -num[i], start = i + 1, end = num.size() - 1;

while (start < end) {

int sum = num[start] + num[end];

if (sum < target)

start++;

else if (sum > target)

end--;

else {

res.push_back({num[i], num[start], num[end]});

while (start < end && num[start] == res.back()[1]) start++;

while (start < end && num[end] == res.back()[2]) end--;

}

}

for (i++; i < num.size() && num[i] == num[i - 1]; i++)

;

}

return res;

}

};

diff --git a/ Problems/0128.cpp b/ Problems/0128.cpp

@@ -0,0 +1,19 @@

class Solution {

public:

int longestConsecutive(vector<int> &nums) {

if (!nums.size()) return 0;

unordered_set<int> us(nums.begin(), nums.end());

int res = 0;

for (int num : us) {

if (!us.count(num - 1)) {

int crnt = num;

while (us.count(crnt + 1)) crnt += 1;

res = max(longestStreak, crnt - num);

}

}

return res + 1;

}

};

diff --git a/ README.md b/ README.md

@@ -26,9 +26,11 @@ for solving problems. | 0001 | Easy | [Two Sum](Problems/0001.cpp) | | 0002 | Medium | [Add Two Numbers](Problems/0002.cpp) | | 0003 | Medium | [Longest Substring Without Repeating Characters](Problems/0003.cpp) |

| 0011 | Medium | [Container With Most Water](Problems/0011.cpp) |

| 0012 | Medium | [Integer to Roman](Problems/0012.cpp) | | 0013 | Easy | [Roman to Integer](Problems/0013.cpp) | | 0014 | Easy | [Longest Common Prefix](Problems/0014.cpp) |

| 0015 | Medium | [3Sum](Problems/0015.cpp) |

| 0019 | Medium | [Remove Nth Node From the End of List](Problems/0019.cpp) | | 0020 | Easy | [Valid Parentheses](Problems/0020.cpp) | | 0021 | Easy | [Merge Two Sorted Lists](Problems/0021.cpp) |

@@ -40,6 +42,7 @@ for solving problems. | 0028 | Medium | [Find the Index of the First Occurrence in a String](Problems/0028.cpp) | | 0035 | Easy | [Search Insert Position](Problems/0035.cpp) | | 0036 | Medium | [Valid Sudoku](Problems/0036.cpp) |

| 0042 | Medium | [Trapping Rain Water](Problems/0011.cpp) |

| 0043 | Medium | [Multiply Strings](Problems/0043.cpp) | | 0049 | Medium | [Group Anagrams](Problems/0049.cpp) | | 0053 | Medium | [Maximum Subarray](Problems/0053.cpp) |

@@ -78,6 +81,7 @@ for solving problems. | 0122 | Medium | [Best Time to Buy and Sell Stock II](Problems/0122.cpp) | | 0124 | Hard | [Binary Tree Maximum Path Sum](Problems/0124.cpp) | | 0125 | Easy | [Valid Palindrome](Problems/0125.cpp) |

| 0128 | Medium | [Longest Consecutive Sequence](Problems/0128.cpp) |

| 0129 | Medium | [Sum Root to Leaf Numbers](Problems/0129.cpp) | | 0131 | Medium | [Palindrome Partitioning](Problems/0131.cpp) | | 0133 | Medium | [Clone Graph](Problems/0133.cpp) |