LeetCode 2015.7.27 64,62,59,466,48,53,113,16

LeetCode 2015.7.27 64,62,59,466,48,53,113,16

64 Minimum Path Sum
class Solution {
public:
int minPathSum(vector< vector<int> >& grid) {
int row = grid.size(), col = grid[0].size();
vector< vector<int> > f;
f.resize(row);
for(int i=0;i<row;i++)
{
for(int j=0;j<col;j++)
{
int up=INT_MAX,left=INT_MAX,tmp;
if (i-1>=0) up = f[i-1][j];
if (j-1>=0) left = f[i][j-1];
if (i==0 && j==0) tmp=0;
else tmp =min(up,left);
f[i].push_back(tmp+grid[i][j]);
}
}
return f[row-1][col-1];
}
};

62 Unique Paths
1.
class Solution {
public:
int uniquePaths(int m, int n) {
int f[m+5][n+5];
for(int i=0;i<=m;i++)
f[i][0] = 0;
for(int i=0;i<=n;i++)
f[0][i] = 0;
f[0][1] = 1;
for(int i=1;i<=m;i++)
for(int j=1;j<=n;j++)
f[i][j] = f[i-1][j] + f[i][j-1];
return f[m]
;
}
};

2.
初始化二维vector
vector<vector<int> > v(m + 1, vector<int>(n + 1, 0));

初始化一维vector
vector<int> x(m+1,0);

59 Spiral Matrix II
class Solution {
public:
vector< vector<int> > generateMatrix(int n) {
vector< vector<int> > f(n+2, vector<int>(n+2,0));
for(int i=0;i<=n+1;i++)
{
f[0][i] = -1;
f[n+1][i] = -1;
f[i][0] = -1;
f[i][n+1] = -1;
}
int dx[4]={0,1,0,-1},dy[4]={1,0,-1,0};
int dir = 0, cnt = 0, total = n*n, x=1, y=0;
while (cnt != total)
{
while (f[x + dx[dir % 4]][y + dy[dir % 4]]==0)
{
x += dx[dir % 4];
y += dy[dir % 4];
cnt++;
f[x][y]=cnt;
}
dir++;
}
vector< vector<int> > ans(n, vector<int> (n));
for(int i=0;i<n;i++)
{
for(int j=0;j<n;j++)
{
ans[i][j]=f[i+1][j+1];
}
}
return ans;
}
};

46 Permutations
1.
class Solution {
public:
vector<bool> flag;
vector< vector<int> > ans;
vector<int> per;
vector< vector<int> > permute(vector<int>& nums) {
flag.resize(nums.size());
per.resize(nums.size());
ans.clear();
for(int i=0;i<flag.size();i++)
{
flag[i]=true;
per[i]=0;
}
depthSearch(0,nums.size(),nums);
return ans;
}
void depthSearch(int k,int n,vector<int> nums) {
if (k==n)
{
ans.push_back(per);
return;
}
for(int i=0;i<n;i++)
if (flag[i])
{
flag[i]=false;
per[k]=nums[i];
depthSearch(k+1,n,nums);
flag[i]=true;
}
return;
}
};

2.
next_permutation
class Solution {
public:
vector< vector<int> > permute(vector<int>& nums) {
sort(nums.begin(),nums.end());
vector< vector<int> > ans;
ans.push_back(nums);
while (next_permutation(nums.begin(),nums.end()))
ans.push_back(nums);
return ans;
}
};

48 Rotate Image
1.
class Solution {
public:
void rotate(vector< vector<int> >& matrix) {
int n = matrix.size();
int f

;
for(int i=0;i<n;i++)
{
for(int j=0;j<n;j++)
{
f[j][n-i-1]=matrix[i][j];
}
}
for(int i=0;i<n;i++)
{
for(int j=0;j<n;j++)
matrix[i][j]=f[i][j];
}
}
};

2.搜的思路
class Solution {
public:
void rotate(vector< vector<int> >& matrix) {
int n=matrix.size()-1;
int m=n/2;
for(int i=0;i<=n;i++)
for(int j=0;j<=i;j++)
{
int tmp = matrix[i][j];
matrix[i][j]=matrix[j][i];
matrix[j][i]=tmp;
}
for(int i=0;i<=n;i++)
for(int j=0;j<=m;j++)
{
int tmp = matrix[i][j];
matrix[i][j] = matrix[i][n-j];
matrix[i][n-j]=tmp;
}
}
};

53 Maximum Subarray
1.
class Solution {
public:
int maxSubArray(vector<int>& nums) {
int ans,n=nums.size();
int f
;
if (nums.size()==0) return 0;
f[0]=nums[0];
ans=nums[0];
for(int i=1;i<n;i++)
{
f[i]=max(nums[i],f[i-1]+nums[i]);
if (f[i]>ans) ans =f[i];
}
return ans;
}
};

113 Path Sum II
class Solution {
public:
vector< vector<int> > ans;
vector<int> route;
vector< vector<int> > pathSum(TreeNode* root, int sum) {
route.clear();
if (root==NULL) return ans;
depthSearch(root,0,sum);
return ans;
}

void depthSearch(TreeNode* root, int tmp, int sum)
{
route.push_back(root->val);
tmp +=root->val;
if (root->left!=NULL) depthSearch(root->left,tmp,sum);
if (root->right!=NULL) depthSearch(root->right,tmp,sum);
if (root->left==NULL && root->right==NULL & tmp==sum)
ans.push_back(route);
route.pop_back();
tmp -=root->val;
return ;
}
};

16 3Sum Closest
class Solution {
public:
int threeSumClosest(vector<int>& nums, int target) {
sort(nums.begin(),nums.end());
int closest = nums[0] + nums[1] + nums[2];
for(int i=0;i<nums.size()-2;i++)
{
if (i>0 & nums[i]==nums[i-1])
continue;
int l = i+1,r=nums.size()-1;
while (l<r)
{
int tmp = nums[i]+nums[l]+nums[r];
if (abs(tmp-target)<abs(closest-target))
closest = tmp;
if (tmp==target)
return target;
else
if (tmp>target)
r--;
else
l++;
}
}
return closest;
}
};