Problem:


Score : 800 points

Problem Statement

There is a grid with R rows and C columns.
We call the cell in the r-th row and c-th column (r，c).

Mr. Takahashi wrote non-negative integers into N of the cells, that is, he wrote a non-negative integer a_i into (r_i，c_i) for each i (1≤i≤N).
After that he fell asleep.

Mr. Aoki found the grid and tries to surprise Mr. Takahashi by writing integers into all remaining cells.
The grid must meet the following conditions to really surprise Mr. Takahashi.

Condition 1: Each cell contains a non-negative integer.

Condition 2: For any 2×2 square formed by cells on the grid, the sum of the top left and bottom right integers must always equal to the sum of the top right and bottom left integers.

Determine whether it is possible to meet those conditions by properly writing integers into all remaining cells.

Constraints

2≤R，C≤10^5

1≤N≤10^5

1≤r_i≤R

1≤c_i≤C

(r_i，c_i) ≠ (r_j，c_j) (i≠j)

a_i is an integer.

0≤a_i≤10^9

Input

The input is given from Standard Input in the following format:

R C
N
r_1 c_1 a_1
r_2 c_2 a_2
:
r_N c_N a_N

Output

Print Yes if it is possible to meet the conditions by properly writing integers into all remaining cells.
Otherwise, print No.

Sample Input 1

2 2
3
1 1 0
1 2 10
2 1 20

Sample Output 1

Yes

You can write integers as follows.

Sample Input 2

2 3
5
1 1 0
1 2 10
1 3 20
2 1 30
2 3 40

Sample Output 2

No

There are two 2×2 squares on the grid, formed by the following cells:

Cells (1，1), (1，2), (2，1) and (2，2)

Cells (1，2), (1，3), (2，2) and (2，3)

You have to write 40 into the empty cell to meet the condition on the left square, but then it does not satisfy the condition on the right square.

Sample Input 3

2 2
3
1 1 20
1 2 10
2 1 0

Sample Output 3

No

You have to write -10 into the empty cell to meet condition 2, but then it does not satisfy condition 1.

Sample Input 4

3 3
4
1 1 0
1 3 10
3 1 10
3 3 20

Sample Output 4

Yes

You can write integers as follows.

Sample Input 5

2 2
4
1 1 0
1 2 10
2 1 30
2 2 20

Sample Output 5

No

All cells already contain a integer and condition 2 is not satisfied.



Sample input:
2 2
3
1 1 0
1 2 10
2 1 20


Sample output:
Yes

Submission status: Runtime Error

Solution code:
def check_squares(grid, coord, isFilled):
    rows, cols = len(grid), len(grid[0])
    r, c = coord[0], coord[1]
    sums = []

    if r - 1 >= 0 and c - 1 >= 0: # check upper left square
        if isFilled and (grid[r][c - 1] + grid[r - 1][c] != grid[r][c] + grid[r - 1][c - 1]):
            raise ValueError('not filled correctly')

        elif not isFilled and if grid[r][c - 1] is not None and grid[r - 1][c] is not None and grid[r - 1][c - 1] is not None:
            sums.append((grid[r][c - 1] + grid[r - 1][c]) - grid[r - 1][c - 1])

    if r - 1 >= 0 and c + 1 < cols: # check upper right square
        if isFilled and (grid[r - 1][c] + grid[r][c + 1] != grid[r][c] + grid[r - 1][c + 1]):
            raise ValueError('not filled correctly')

        elif not isFilled and grid[r - 1][c] is not None and grid[r - 1][c + 1] is not None and grid[r][c + 1] is not None:
            sums.append((grid[r - 1][c] + grid[r][c + 1]) - grid[r - 1][c + 1])

    if r + 1 < rows and c - 1 >= 0: # check lower left
        if isFilled and (grid[r][c] + grid[r + 1][c - 1] != grid[r][c - 1] + grid[r + 1][c]):
            raise ValueError('not filled correctly')

        elif not isFilled and grid[r][c - 1] is not None and grid[r + 1][c] is not None and grid[r + 1][c - 1] is not None:
            sums.append((grid[r][c - 1] + grid[r + 1][c]) - grid[r + 1][c - 1])

    if r + 1 < rows and c + 1 < cols: # check lower right
        if isFilled and (grid[r + 1][c + 1] + grid[r][c] != grid[r][c + 1] + grid[r + 1][c]):
            raise ValueError('not filled correctly')

        elif not isFilled and grid[r][c + 1] is not None and grid[r + 1][c] is not None and grid[r + 1][c + 1] is not None:
            sums.append((grid[r + 1][c] + grid[r][c + 1]) - grid[r + 1][c + 1])

    if len(sums) > 1 and len(set(sums)) > 1:
        raise ValueError('Square cannot be filled in')
    elif len(sums) == 1:
        if sums[0] < 0:
            raise ValueError('Value would have to be negative')
        return sums[0]
    else:
        return None

r, c = map(int, raw_input().split())
n = int(raw_input())
grid = [ [None for i in range(c)] for j in range(r) ]

for i in range(n):
    line = map(int, raw_input().split())
    grid[line[0] - 1][line[1] - 1] = line[2]


possible = True
filled = (n == r * c)
for i in range(r):
    for j in range(c):
        if grid[i][j] is None or filled:
            try:
                result = check_squares(grid, (i, j), filled)
                if not filled:
                    grid[i][j] = result
            except ValueError:
                print 'No'
                exit()

print 'Yes'

Submission status: Runtime Error

Solution code:
def check_squares(grid, coord, isFilled):
    rows, cols = len(grid), len(grid[0])
    r, c = coord[0], coord[1]
    sums = []

    if r - 1 >= 0 and c - 1 >= 0: # check upper left square
        if isFilled and (grid[r][c - 1] + grid[r - 1][c] != grid[r][c] + grid[r - 1][c - 1]):
            raise ValueError('not filled correctly')

        elif not isFilled and if grid[r][c - 1] is not None and grid[r - 1][c] is not None and grid[r - 1][c - 1] is not None:
            sums.append((grid[r][c - 1] + grid[r - 1][c]) - grid[r - 1][c - 1])

    if r - 1 >= 0 and c + 1 < cols: # check upper right square
        if isFilled and (grid[r - 1][c] + grid[r][c + 1] != grid[r][c] + grid[r - 1][c + 1]):
            raise ValueError('not filled correctly')

        elif not isFilled and grid[r - 1][c] is not None and grid[r - 1][c + 1] is not None and grid[r][c + 1] is not None:
            sums.append((grid[r - 1][c] + grid[r][c + 1]) - grid[r - 1][c + 1])

    if r + 1 < rows and c - 1 >= 0: # check lower left
        if isFilled and (grid[r][c] + grid[r + 1][c - 1] != grid[r][c - 1] + grid[r + 1][c]):
            raise ValueError('not filled correctly')

        elif not isFilled and grid[r][c - 1] is not None and grid[r + 1][c] is not None and grid[r + 1][c - 1] is not None:
            sums.append((grid[r][c - 1] + grid[r + 1][c]) - grid[r + 1][c - 1])

    if r + 1 < rows and c + 1 < cols: # check lower right
        if isFilled and (grid[r + 1][c + 1] + grid[r][c] != grid[r][c + 1] + grid[r + 1][c]):
            raise ValueError('not filled correctly')

        elif not isFilled and grid[r][c + 1] is not None and grid[r + 1][c] is not None and grid[r + 1][c + 1] is not None:
            sums.append((grid[r + 1][c] + grid[r][c + 1]) - grid[r + 1][c + 1])

    if len(sums) > 1 and len(set(sums)) > 1:
        raise ValueError('Square cannot be filled in')
    elif len(sums) == 1:
        if sums[0] < 0:
            raise ValueError('Value would have to be negative')
        return sums[0]
    else:
        return None

r, c = map(int, raw_input().split())
n = int(raw_input())
grid = [ [None for i in range(c)] for j in range(r) ]

for i in range(n):
    line = map(int, raw_input().split())
    grid[line[0] - 1][line[1] - 1] = line[2]


filled = (n == r * c)
for i in range(r):
    for j in range(c):
        if grid[i][j] is None or filled:
            try:
                result = check_squares(grid, (i, j), filled)
                grid[i][j] = result
            except ValueError:
                print 'No'
                exit()

print 'Yes'

Submission status: Runtime Error

Solution code:
c,r = map(int, input().split())
N=int(input())
list=[[-1] * r for i in range(c)]
for i in range(N):
    i1,i1,x=map(int, input().split()))
    list[i1][i2]=x
print('Yes')

Submission status: Runtime Error

Solution code:
def checker(board):
    #for (upper,under) in zip(board[0],board[1])
    upper = board[0]
    under = board[1]
    numlist = []
    for i in range(len(upper)-2):
        try:
            tmp = upper[i] + under[i+1]
            numlist.append(tmp)
            tmp2 = upper[i+1] + under[i]
            numlist.append(tmp2)
        except:
            pass

    if len(list(set(numlist))) == 1:
        return 'Yes'
    elif:
        return 'No'


R,C = map(int,raw_input().split())
N = input()

a = []
for i in xrange(N):
    a.append(map(int,raw_input().split()))

#matrix
ans_board =	[['None' for i in xrange(C)],
         ['None' for i in xrange(C)]]

for a_sub in a:
    ans_board[a_sub[0]-1][a_sub[1]-1] = a_sub[2]

print checker(ans_board)

Submission status: Runtime Error

Solution code:
def checker(board):
    #for (upper,under) in zip(board[0],board[1])
    upper = board[0]
    under = board[1]
    numlist = []
    for i in range(len(upper)-2):
        try:
            tmp = upper[i] + under[i+1]
            numlist.append(tmp)
            tmp2 = upper[i+1] + under[i]
            numlist.append(tmp2)
        except:
            pass

    if len(list(set(numlist))) == 1:
        return 'yes'
    elif:
        return 'no'



R,C = map(int,raw_input().split())
N = input()

a = []
for i in xrange(N):
    a.append(map(int,raw_input().split()))

#matrix
ans_board =	[['None' for i in xrange(C)],
         ['None' for i in xrange(C)]]

for a_sub in a:
    ans_board[a_sub[0]-1][a_sub[1]-1] = a_sub[2]