strudel

#include <stdio.h>
#include <assert.h>

#define MAXN 100000

int diff[MAXN];

bool f(int test, int N){
    int sum = 0;
    for(int i=0;i<test;i++)
        sum += diff[i];
    if(sum >= 0)
        return true;

    for(int i=1;i+test-1<N;i++){
        sum -= diff[i-1];
        sum += diff[i+test-1];
        if(sum >= 0)
            return true;
    }
    return false;
}

int porziona(int N, int mandorle[], int cannella[]) {
    int answer = -1;
    int lb = 1;
    int ub = N;

    for(int i=0;i<N;i++)
        diff[i] = cannella[i] - mandorle[i];

    while(lb <= ub){
        int test = lb + (ub - lb)/2;
        if(f(test, N)){
            answer = test;
            lb = test + 1;
        }
        else
            ub = test - 1;
    }

    return answer;
}


int mandorle[MAXN], cannella[MAXN];

int main() {
    FILE *fr, *fw;
    int N, i;

    fr = fopen("input.txt", "r");
    fw = fopen("output.txt", "w");
    assert(1 == fscanf(fr, "%d", &N));
    for(i=0; i<N; i++)
        assert(1 == fscanf(fr, "%d", &mandorle[i]));
    for(i=0; i<N; i++)
        assert(1 == fscanf(fr, "%d", &cannella[i]));

    fprintf(fw, "%d\n", porziona(N, mandorle, cannella));
    fclose(fr);
    fclose(fw);
    return 0;
}