Question

Can someone tell me how to fix warning msg in my code of C ++?

I got run-time error for this question please help me asap!

Errors are:
In function 'void bfs(int, int)':
warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 for(int j = 0; j < adj[pppp].size(); j++){
                  ^
In function 'int main()':
warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
 scanf("%d %d %d %d %d", &a, &q, &c, &N, &m);
                                            ^
warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
 scanf("%d %d", &fir, &bbb);
                         ^

#include <iostream>

#include <stdio.h>

#include <vector>

#include <algorithm>

#include <queue>

int min(int n,int arr[]){

int m=arr[0];

for(int i=1;i<n;i++)

if(m>arr[i])

m=arr[i];

return m;

}

using namespace std;

const int Max_max = 404040;

const int INF = 1e7;

int sum[Max_max];

int a,q,c,N,m,fir;

vector<int> adj[Max_max];

void bfs(int money, int start_node){

bool hello[Max_max];

for(int i=0; i<=N; i++)

hello[i] = false;

queue<int> q;

q.push(start_node);

hello[start_node] = true;

int distance = 1;

do{

int size = q.size();

for(int i = 0; i < size; i++){

int pppp = q.front(); q.pop();

for(int j = 0; j < adj[pppp].size(); j++){ //error undeclared identifier 'ppp_city'

int next = adj[pppp][j];

if(hello[next])

continue;

sum[pppp] += money * distance;

hello[next] = true;

q.push(next);

}

}

distance++;

} while (q.size() > 0);

}

int main(){

scanf("%d %d %d %d %d", &a, &q, &c, &N, &m);

for(int i=0; i < m; i++){

int aaa, bbb;

scanf("%d %d", &fir, &bbb);

adj[aaa].push_back(bbb);

adj[bbb].push_back(aaa);

}

bfs(a,1);

bfs(q,2);

bfs(c,N);

int fin = INF;

for(int i = 1; i <= N; i++)

fin = min(fin, sum); //error no matching function to call min

printf("%d",fin);

return 0;

}

Answer 1

If you have any doubts, please give me comment...

#include <iostream>

#include <stdio.h>

#include <vector>

#include <algorithm>

#include <queue>

int min(int n, int arr[])

{

    int m = arr[0];

    for (int i = 1; i < n; i++)

        if (m > arr[i])

            m = arr[i];

    return m;

}

using namespace std;

const int Max_max = 404040;

const int INF = 1e7;

int sum[Max_max];

int a, q, c, N, m, fir;

vector<int> adj[Max_max];

void bfs(int money, int start_node)

{

    bool hello[Max_max];

    for (int i = 0; i <= N; i++)

        hello[i] = false;

    queue<int> q;

    q.push(start_node);

    hello[start_node] = true;

    int distance = 1;

    do

    {

        int size = q.size();

        for (int i = 0; i < size; i++)

        {

            int pppp = q.front();

            q.pop();

            for (size_t j = 0; j < adj[pppp].size(); j++)

            { //error undeclared identifier 'ppp_city'

                int next = adj[pppp][j];

                if (hello[next])

                    continue;

                sum[pppp] += money * distance;

                hello[next] = true;

                q.push(next);

            }

        }

        distance++;

    } while (q.size() > 0);

}

int main()

{

    int result = scanf("%d %d %d %d %d", &a, &q, &c, &N, &m);

    if(result!=5)

        printf("input error!\n");

    for (int i = 0; i < m; i++)

    {

        int aaa, bbb;

        result = scanf("%d %d", &fir, &bbb);

        adj[aaa].push_back(bbb);

        adj[bbb].push_back(aaa);

    }

    bfs(a, 1);

    bfs(q, 2);

    bfs(c, N);

    int fin = INF;

    for (int i = 1; i <= N; i++)

        fin = min(fin, sum); //error no matching function to call min

    printf("%d", fin);

    return 0;

}