第一周实验

第一题

#include <stdio.h>
#include <time.h>
#include <math.h>

clock_t start, stop;
double duration;
#define MAXN 10
#define MAXK 1e7

double f1(int n, double a[], double x) {
    int i;
    double p = a[0];
    for (i = 1; i <= n; i++)
        p += (a[i] * pow(x, i));
    return p;
}

double f2(int n, double a[], double x) {
    int i;
    double p = a[n];
    for(i = n; i > 0; i--)
        p = a[i - 1] + x * p;
    return p;
}

void run(double(*f)(int, double *, double), double a[], int case_n) {
    int i;


    start = clock();
    for(i = 0; i < MAXK; i++)
        (*f)(MAXN - 1, a, 1.1);

    stop = clock();

    duration = ((double)(stop - start)) / CLK_TCK / MAXK;
    printf("ticks%d=%f\n", case_n, (double)(stop - start));
    printf("duration%d=%6.2e\n", case_n, duration);
}

int main() {
    int i;
    double a[MAXN];

    for(i = 0; i < MAXN; i++)
        a[i] = (double)i;

    run(f1, a, 1);
    run(f2, a, 2);
    return 0;
}

第二题

/*
 * ==================================================================================
 * Author:  north_h
 * Time:    2023-09-10 21:22:37
 *
 * Problem: P1115 最大子段和
 * Contest: Luogu
 * URL:     https://www.luogu.com.cn/problem/P1115
 * MemoryL: 125 MB
 * TimeL:   1000 ms
 * ==================================================================================
 */

#include<stdio.h>
int main() {
    int n;
    scanf("%d", &n);
    int sum = 0;
    int ans = -2e9;
    for(int i = 0; i < n; i++) {
        int x;
        scanf("%d", &x);
        sum += x;
        // printf("%d-%d\n", sum, ans);
        if(ans < sum)ans = sum;
        // printf("%d-%d\n", sum, ans);
        if(sum < 0) {
            sum = 0;
        }
    }
    if(ans < sum && sum != 0)ans = sum;
    printf("%d", ans);
    return 0;
}