Submission #10231049

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int MAX = 1e5 + 10;
int prime[MAX], tag[MAX], f[MAX];
void is_Prime(){
	int cnt = 0;
	prime[++cnt] = 2;
	tag[1] = 1;
	for( int i = 2; i < MAX; i++){
		if(!tag[i])
			prime[++cnt] = i;
		for(int j = 1; j <= cnt && i * prime[j] < MAX; j++){
			tag[i * prime[j]] = 1;
			if( i % prime[j] == 0)
				break;
		}
	}
}
int main(){
	int t, l, r, num = 0;
	is_Prime();
	
	for (int i=1; i <= MAX; i++)
    {
        if(tag[i] == 0 && tag[(i+1)/2] == 0 && i != 2)
            {
                f[i]=f[i-1]+1;
            }
        else f[i]=f[i-1];
    }
    
	cin >> t;
	while(t--){
		scanf("%d%d", &l, &r);
		printf("%d\n", f[r] - f[l - 1]);
	}
	return  0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:35:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &l, &r);
                        ^
./Main.cpp:26:17: warning: iteration 100009u invokes undefined behavior [-Waggressive-loop-optimizations]
         if(tag[i] == 0 && tag[(i+1)/2] == 0 && i != 2)
                 ^
./Main.cpp:24:18: note: containing loop
  for (int i=1; i <= MAX; i++)
                  ^

Judge Result