Buggy python submission (verdict: Time Limit Exceeded):
n, s = [int(i) for i in  input().split()]
weights = []
values = []

for _ in range(n):
    w, v = [int(i) for i in input().split()]
    weights.append(w)
    values.append(v)

def knapsack(weights, values, limit):
    n = len(weights)
    # f = [[0 for _ in range(limit+1)] for _ in range(n)]

    prev = [0 for _ in range(limit+1)]

    if weights[0] <= limit:
        for w in range(weights[0], limit+1):
            prev[w] = values[0]

    for i in range(1, n):
        # print prev
        current = [0] * (limit+1)
        for w in range(1, limit+1):
            current[w] = max(prev[w], current[w])
            if weights[i] <= w:
                current[w] = max(current[w], prev[w-weights[i]] + values[i])
        prev = list(current)

    return prev[-1]

# weights = [10, 20, 30]
# values = [60, 100, 120]
print(knapsack(weights, values, s))

Fixed submission:
n, s = [int(i) for i in  raw_input().split()]
weights = []
values = []

for _ in xrange(n):
    w, v = [int(i) for i in raw_input().split()]
    weights.append(w)
    values.append(v)

def knapsack(weights, values, limit):
    n = len(weights)
    # f = [[0 for _ in xrange(limit+1)] for _ in xrange(n)]

    prev = [0 for _ in xrange(limit+1)]

    if weights[0] <= limit:
        for w in xrange(weights[0], limit+1):
            prev[w] = values[0]

    for i in xrange(1, n):
        # print prev
        current = [0] * (limit+1)
        for w in xrange(1, limit+1):
            current[w] = max(prev[w], current[w])
            if weights[i] <= w:
                current[w] = max(current[w], prev[w-weights[i]] + values[i])
        prev = list(current)

    return prev[-1]

# weights = [10, 20, 30]
# values = [60, 100, 120]
print(knapsack(weights, values, s))

Buggy python submission (verdict: Time Limit Exceeded):
n, s = [int(i) for i in  raw_input().split()]
weights = []
values = []

for _ in xrange(n):
    w, v = [int(i) for i in raw_input().split()]
    weights.append(w)
    values.append(v)

def knapsack(weights, values, limit):
    n = len(weights)
    # f = [[0 for _ in xrange(limit+1)] for _ in xrange(n)]

    prev = [0 for _ in xrange(limit+1)]

    if weights[0] <= limit:
        for w in xrange(weights[0], limit+1):
            prev[w] = values[0]

    for i in xrange(1, n):
        # print prev
        current = [0] * (limit+1)
        for w in xrange(1, limit+1):
            current[w] = max(prev[w], current[w])
            if weights[i] <= w:
                current[w] = max(current[w], prev[w-weights[i]] + values[i])
        prev = list(current)

    return prev[-1]

# weights = [10, 20, 30]
# values = [60, 100, 120]
print(knapsack(weights, values, s))

Fixed submission:
n, s = [int(i) for i in  raw_input().split()]
weights = []
values = []

for _ in xrange(n):
    w, v = [int(i) for i in raw_input().split()]
    weights.append(w)
    values.append(v)

def knapsack(weights, values, limit):
    n = len(weights)
    # f = [[0 for _ in xrange(limit+1)] for _ in xrange(n)]

    prev = [0 for _ in xrange(limit+1)]

    if weights[0] <= limit:
        for w in xrange(weights[0], limit+1):
            prev[w] = values[0]

    for i in xrange(1, n):
        # print prev
        current = [0] * (limit+1)
        for w in xrange(1, limit+1):
            current[w] = max(prev[w], current[w])
            if weights[i] <= w:
                current[w] = max(current[w], prev[w-weights[i]] + values[i])
        prev = list(current)

    return prev[-1]

# weights = [10, 20, 30]
# values = [60, 100, 120]
print(knapsack(weights, values, s))

Buggy python submission (verdict: Time Limit Exceeded):
n, s = [int(i) for i in  raw_input().split()]
weights = []
values = []

for _ in range(n):
    w, v = [int(i) for i in raw_input().split()]
    weights.append(w)
    values.append(v)

def knapsack(weights, values, limit):
    n = len(weights)
    # f = [[0 for _ in range(limit+1)] for _ in range(n)]

    prev = [0 for _ in range(limit+1)]

    if weights[0] <= limit:
        for w in range(weights[0], limit+1):
            prev[w] = values[0]

    for i in range(1, n):
        # print prev
        current = [0] * (limit+1)
        for w in range(1, limit+1):
            current[w] = max(prev[w], current[w])
            if weights[i] <= w:
                current[w] = max(current[w], prev[w-weights[i]] + values[i])
        prev = list(current)

    return prev[-1]

# weights = [10, 20, 30]
# values = [60, 100, 120]
print(knapsack(weights, values, s))

Fixed submission:
n, s = [int(i) for i in  raw_input().split()]
weights = []
values = []

for _ in xrange(n):
    w, v = [int(i) for i in raw_input().split()]
    weights.append(w)
    values.append(v)

def knapsack(weights, values, limit):
    n = len(weights)
    # f = [[0 for _ in xrange(limit+1)] for _ in xrange(n)]

    prev = [0 for _ in xrange(limit+1)]

    if weights[0] <= limit:
        for w in xrange(weights[0], limit+1):
            prev[w] = values[0]

    for i in xrange(1, n):
        # print prev
        current = [0] * (limit+1)
        for w in xrange(1, limit+1):
            current[w] = max(prev[w], current[w])
            if weights[i] <= w:
                current[w] = max(current[w], prev[w-weights[i]] + values[i])
        prev = list(current)

    return prev[-1]

# weights = [10, 20, 30]
# values = [60, 100, 120]
print(knapsack(weights, values, s))

Buggy python submission (verdict: Time Limit Exceeded):
n, s = [int(i) for i in  raw_input().split()]
weights = []
values = []

for _ in range(n):
    w, v = [int(i) for i in raw_input().split()]
    weights.append(w)
    values.append(v)

def knapsack(weights, values, limit):
    n = len(weights)
    f = [[0 for _ in range(limit+1)] for _ in range(n)]

    if weights[0] <= limit:
        for w in range(weights[0], limit+1):
            f[0][w] = values[0]

    for w in range(1, limit+1):
        for i in range(1, n):
            f[i][w] = max(f[i-1][w], f[i][w])
            if weights[i] <= w:
                f[i][w] = max(f[i][w], f[i-1][w-weights[i]] + values[i])

    return f[-1][-1]

# weights = [10, 20, 30]
# values = [60, 100, 120]
print(knapsack(weights, values, s))

Fixed submission:
n, s = [int(i) for i in  raw_input().split()]
weights = []
values = []

for _ in xrange(n):
    w, v = [int(i) for i in raw_input().split()]
    weights.append(w)
    values.append(v)

def knapsack(weights, values, limit):
    n = len(weights)
    # f = [[0 for _ in xrange(limit+1)] for _ in xrange(n)]

    prev = [0 for _ in xrange(limit+1)]

    if weights[0] <= limit:
        for w in xrange(weights[0], limit+1):
            prev[w] = values[0]

    for i in xrange(1, n):
        # print prev
        current = [0] * (limit+1)
        for w in xrange(1, limit+1):
            current[w] = max(prev[w], current[w])
            if weights[i] <= w:
                current[w] = max(current[w], prev[w-weights[i]] + values[i])
        prev = list(current)

    return prev[-1]

# weights = [10, 20, 30]
# values = [60, 100, 120]
print(knapsack(weights, values, s))

Buggy python submission (verdict: Runtime Error):
s, n = [int(i) for i in  raw_input().split()]
weights = []
values = []

for _ in range(n):
    w, v = [int(i) for i in raw_input().split()]
    weights.append(w)
    values.append(v)

def knapsack(weights, values, limit):
    n = len(weights)
    f = [[0 for _ in range(limit+1)] for _ in range(n)]

    if weights[0] <= limit:
        for w in range(weights[0], limit):
            f[0][w] = values[0]

    for w in range(1, limit+1):
        for i in range(1, n):
            f[i][w] = max(f[i-1][w], f[i][w])
            if weights[i] <= w:
                f[i][w] = max(f[i][w], f[i-1][w-weights[i]] + values[i])

    return f[-1][-1]

# weights = [10, 20, 30]
# values = [60, 100, 120]
print(knapsack(weights, values, s))

Fixed submission:
n, s = [int(i) for i in  raw_input().split()]
weights = []
values = []

for _ in xrange(n):
    w, v = [int(i) for i in raw_input().split()]
    weights.append(w)
    values.append(v)

def knapsack(weights, values, limit):
    n = len(weights)
    # f = [[0 for _ in xrange(limit+1)] for _ in xrange(n)]

    prev = [0 for _ in xrange(limit+1)]

    if weights[0] <= limit:
        for w in xrange(weights[0], limit+1):
            prev[w] = values[0]

    for i in xrange(1, n):
        # print prev
        current = [0] * (limit+1)
        for w in xrange(1, limit+1):
            current[w] = max(prev[w], current[w])
            if weights[i] <= w:
                current[w] = max(current[w], prev[w-weights[i]] + values[i])
        prev = list(current)

    return prev[-1]

# weights = [10, 20, 30]
# values = [60, 100, 120]
print(knapsack(weights, values, s))