用C语言运行的时候跳出空白控制窗口,用c++来运行该代码却可以正常运行;KMP算法子串查找


#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>
using namespace std;
const int N = 10010, M = 100010;
int n, m;
char p[N], s[M];
int ne[N];

int main() {
    freopen("in.txt", "r", stdin);
    scanf("%d", &n);
    for (int i = 1; i <= n; i++) scanf(" %c", &p[i]);
    scanf("%d", &m);
    for (int i = 1; i <= m; i++) scanf(" %c", &s[i]);
    //求next的过程
    for (int i = 2, j = 0; i <= n; i++) {
        while (j && p[i] != p[j + 1]) j = ne[j];
        if (p[i] == p[j + 1]) j++;
        ne[i] = j;
    }
    //kmp 匹配过程
    for (int i = 1, j = 0; i <= m; i++) {
        while (j && s[i] != p[j + 1]) j = ne[j];
        if (s[i] == p[j + 1]) j++;
        if (j == n) {
            printf("%d ", i - n);
            j = ne[j];
        }
    }
    return 0;
}

#include<stdio.h>
const int N = 10010,M =100010;
char q[N], s[M];
int ne[N];
int main() {
    freopen("in.txt", "r", stdin);
    int n, m;
    scanf("%d", &n);
    for (int i = 1; i <= n; i++) scanf(" %c", &q[i]);
    scanf("%d", &m);
    for (int i = 1; i <= m; i++) scanf(" %c", &s[i]);
    //标记next数组,
    for (int i = 2,j = 0; i <= n; i++) {
        while (j && q[i] != q[j + 1]) j = ne[i];
        if (q[i] == q[j + 1]) j++;
        ne[i] = j;
    }
    for (int i = 1, j = 0; i <= m; i++) {
        while (j && s[i] != q[j + 1]) j = ne[i];
        if (s[i] == q[j + 1]) j++;
        if (j == n) {
            printf("%d", i - n);
            j = ne[j];
        }
    }
    return 0;
}

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输出 : 7

C语言输出结果

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C++输出结果

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c语言不能用const int N = 10010,M =100010;
改成

#define N 10010
#define M 100010

for循环中 scanf(" %c", &q[i]);//%c前面多了个空格
应该改成 for (int i = 1; i <= n; i++){getchar(); scanf("%c", &q[i]);}
最主要的是你c++代码是 j = ne[j];, c的代码却写成了是 j = ne[i];

你题目的解答代码如下:

#include<stdio.h>
//const int N = 10010,M =100010;
#define N 10010
#define M 100010
char q[N], s[M];
int ne[N];
int main() {
    freopen("in.txt", "r", stdin);
    int n, m;
    scanf("%d", &n);
    for (int i = 1; i <= n; i++){getchar(); scanf("%c", &q[i]);}
    scanf("%d", &m);
    for (int i = 1; i <= m; i++){getchar(); scanf("%c", &s[i]);}
    //标记next数组,
    for (int i = 2,j = 0; i <= n; i++) {
        while (j && q[i] != q[j + 1]) j = ne[j]; // ne[i]改成ne[j]
        if (q[i] == q[j + 1]) j++;
        ne[i] = j;
    }
    for (int i = 1, j = 0; i <= m; i++) {
        while (j && s[i] != q[j + 1]) j = ne[j]; // ne[i]改成ne[j]
        if (s[i] == q[j + 1]) j++;
        if (j == n) {
            printf("%d", i - n);
            j = ne[j];
        }
    }
    return 0;
}

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int ne[N]; 没有初始化