《算法竞赛入门经典》第三章思考题

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#include <stdio.h>
#include <stdlib.h>

void count() // 1题
{
    int n, ct = 0;
    while(1 == scanf("%d", &n))
        ++ct;
    printf("You've inputted %d numbersn", ct);
}

void maxMinAverage() // 2题
{
    int n, max, min, sum = 0, ct = 0, first = 1;
    while(1 == scanf("%d", &n))
    {
        if(first) { max = min = n; first = 0; }
        if(max < n) max = n;
        if(n < min) min = n;
        sum += n;
        ++ct;
    }
    printf("max:%d min:%d average:%.3fn", max, min, sum*1.0/ct);
}

void nearest() // 3题
{
    int nums[100], i = 0, j, k;
    while(1 == scanf("%d", &nums[i]))
        ++i;
    printf("%dn", i);
    int a = nums[0], b = nums[1], distance = abs(nums[0]-nums[1]);
    for(j = 0; j < i - 1; ++j)
        for(k = j + 1; k < i; ++k)
            if(abs(nums[j]-nums[k]) < distance)
            {
                distance = abs(nums[j]-nums[k]);
                a = nums[j];
                b = nums[k];
            }
    printf("two nearest numbers: %d %d, distance: %dn", a, b, distance);
}

void second() // 4题
{
    int max, second, n;
    scanf("%d%d", &max, &second);
    int t1 = max > second ? max : second;
    int t2 = max < second ? max : second;
    max = t1; second = t2;
    //printf("max:%d second:%dn", max, second);
    while(1 == scanf("%d", &n))
    {
        if(n > max) { second = max; max = n; continue; }
        if(n > second && n != max) second = n;
    }
    printf("max:%d second:%dn", max, second);
}

void variance() // 5题
{
    int nums[100];
    int ct = 0, n, i;
    double ave = 0.0, sum = 0.0, psum = 0.0;
    while(1 == scanf("%d", &n))
    {
        nums[ct++] = n;
        sum += n;
    }
    ave = sum / ct;
    for(i = 0; i < ct; ++i)
        psum += (nums[i] - ave) * (nums[i] - ave);
    printf("variance: %.3fn", psum / ct);
}

void smallerThanAve() // 6题
{
    int nums[100];
    int ct = 0, sct = 0, n, i;
    double ave = 0.0, sum = 0.0;
    while(1 == scanf("%d", &n))
    {
        nums[ct++] = n;
        sum += n;
    }
    ave = sum / ct;
    for(i = 0; i < ct; ++i)
        if(nums[i] < ave) ++sct;
    printf("%d numbers smaller than average %fn", sct, ave);
}

int main()
{
    //count();
    //maxMinAverage();
    //nearest();
    //second();
    //variance();
    //smallerThanAve();
    return 0;
}

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#include<stdio.h>
#define maxn 10000000 + 10
int main()
{
    char s[maxn];
    scanf("%s", s);
    int tot = 0;
    for(int i = 0; i < strlen(s); i++)
        if(s[i] == 1) tot++;
    printf("%dn", tot);
}

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#include <stdio.h>

int main()
{
    int tot = 0;
    char ch;
    while((ch = getchar()) != EOF)
        if(ch == '1') ++tot;
    printf("%dn", tot);
}