本文介绍了排序功能C ++分段错误的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

问题描述

在此代码中,对于向量大小n> = 32767,它给出了分段错误,但直到32766,它运行良好.可能是什么错误?这是完整的代码.

In this code, for vector size, n >=32767, it gives segmentation fault, but upto 32766, it runs fine. What could be the error? This is full code.

#include<cstdio>
#include<cstring>
#include<cmath>
#include<queue>
#include<utility>
#include<algorithm>
#include<sys/time.h>
using namespace std;
#define MAX 100000

bool compare(pair<int,int> p1,pair<int,int> p2) {
    if(p1.second < p2.second)
        return 1;
    else if(p1.second > p2.second)
        return 0;
    if(p1.first <= p2.first)
        return 1;
    else
        return 0;
}

int main() {
    freopen("randomin.txt","r",stdin);
    int n;
    scanf("%d",&n);
    vector< pair<int,int> > p(n);
    for(int i=0;i<n;i++)
        scanf("%d%d",&p[i].first,&p[i].second);
    **printf("%d\n",(int)p.max_size()); // prints 536870911**
    sort(p.begin(),p.begin()+n,compare);

    //for(int i=0;i<n;i++)
        //printf("%d %d\n",p[i].first,p[i].second);
        printf("%.6f\n",(p[n-1].second+p[n-2].second)/(20.0+p[n-1].first+p[n-2].first));

    return 0;
}

推荐答案

这可能与您的细分错误无关,但是...

This may be unrelated to your segmentation fault, but...

在C ++中,您的比较"谓词必须为严格弱排序 .特别是,"compare(X,X)"必须为任何X返回"false".在比较函数中,如果两对相同,则击中测试(p1.first <= p2.first),并返回"true".因此,此比较"谓词没有施加严格的弱排序,并且将其传递给排序"的结果是不确定的.

In C++, your "compare" predicate must be a strict weak ordering. In particular, "compare(X,X)"must return "false" for any X. In your compare function, if both pairs are identical, you hit the test (p1.first <= p2.first) , and return "true". Therefore, this "compare" predicate does not impose a strict weak ordering, and the result of passing it to "sort" is undefined.

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08-21 19:28