def GetNext(t,next): #由模式串t求出next值 next[0] = -1 i,j=0,-1 while i < len(t) - 1: if j == -1 or t[i] == t[j]: i,j=i+1, j+1 next[i] = j else: j=next def StrCount2(s, t): # KMP算法求解 i, j, cnt = 0, 0, 0 next = [-1] * len(t) GetNext(t, next) while i < len(s): if j == -1 or s[i] == t[j]: i, j = i + 1, j + 1 else: j = next[j] if j == len(t): cnt += 1 j = 0 return cnt

这段代码存在一些问题，我将逐一列举并给出修改建议：

1. GetNext 函数中的第 7 行和第 9 行缺少缩进，导致语法错误。正确的代码应该是：

def GetNext(t, next):
    next[0] = -1
    i, j = 0, -1
    while i < len(t) - 1:
        if j == -1 or t[i] == t[j]:
            i, j = i + 1, j + 1
            next[i] = j
        else:
            j = next[j]

2. GetNext 函数中的第 8 行和第 10 行缺少 j 的更新，导致 next 数组计算错误。正确的代码应该是：

def GetNext(t, next):
    next[0] = -1
    i, j = 0, -1
    while i < len(t) - 1:
        if j == -1 or t[i] == t[j]:
            i, j = i + 1, j + 1
            next[i] = j if t[i] != t[j] else next[j]
        else:
            j = next[j]

3. StrCount2 函数中的第 10 行缺少缩进，导致语法错误。正确的代码应该是：

def StrCount2(s, t):
    # KMP算法求解
    i, j, cnt = 0, 0, 0
    next = [-1] * len(t)
    GetNext(t, next)
    while i < len(s):
        if j == -1 or s[i] == t[j]:
            i, j = i + 1, j + 1
        else:
            j = next[j]
        if j == len(t):
            cnt += 1
            j = 0
    return cnt

综上所述，修改后的代码如下：

def GetNext(t, next):
    next[0] = -1
    i, j = 0, -1
    while i < len(t) - 1:
        if j == -1 or t[i] == t[j]:
            i, j = i + 1, j + 1
            next[i] = j if t[i] != t[j] else next[j]
        else:
            j = next[j]

def StrCount2(s, t):
    # KMP算法求解
    i, j, cnt = 0, 0, 0
    next = [-1] * len(t)
    GetNext(t, next)
    while i < len(s):
        if j == -1 or s[i] == t[j]:
            i, j = i + 1, j + 1
        else:
            j = next[j]
        if j == len(t):
            cnt += 1
            j = 0
    return cnt