Buggy python submission (verdict: Runtime Error):
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, min(limit+1, sum(values))):
            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 = []

f = [float("inf") for i in xrange(100001)]
f[0] = 0

for _ in xrange(n):
    w, v = [int(i) for i in raw_input().split()]
    
    for x in range(100000-v, -1, -1):
        f[x+v] = min(f[x+v], f[x] + w)

# print f[:100]

a = max([i for i in xrange(100001) if f[i] <= s])
print a

Buggy python submission (verdict: Runtime Error):
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 = []

f = [float("inf") for i in xrange(100001)]
f[0] = 0

for _ in xrange(n):
    w, v = [int(i) for i in raw_input().split()]
    
    for x in range(100000-v, -1, -1):
        f[x+v] = min(f[x+v], f[x] + w)

# print f[:100]

a = max([i for i in xrange(100001) if f[i] <= s])
print a

Buggy python submission (verdict: Runtime Error):
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 = []

f = [float("inf") for i in xrange(100001)]
f[0] = 0

for _ in xrange(n):
    w, v = [int(i) for i in raw_input().split()]
    
    for x in range(100000-v, -1, -1):
        f[x+v] = min(f[x+v], f[x] + w)

# print f[:100]

a = max([i for i in xrange(100001) if f[i] <= s])
print a

Buggy python submission (verdict: Runtime Error):
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 = []

f = [float("inf") for i in xrange(100001)]
f[0] = 0

for _ in xrange(n):
    w, v = [int(i) for i in raw_input().split()]
    
    for x in range(100000-v, -1, -1):
        f[x+v] = min(f[x+v], f[x] + w)

# print f[:100]

a = max([i for i in xrange(100001) if f[i] <= s])
print a