算法笔记-第四章简单贪心题解

背景

目前算法笔记的学习已经进展到第四章，下面会记录第四章贪心算法的两道题解。写这篇博客的目的也是鼓励自己继续学习下去。

简单贪心

PAT B1020

#include <stdio.h>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <cmath>

using namespace std;

struct Mooncake {
    double store;//库存量，单位万吨
    double saleprice;//总售价，单位亿元
    double perStorePrice;//总售价/库存量，单价
} mooncake[1000];

bool cmpMoon(Mooncake a, Mooncake b) {
    //单价高的排在前面
    return a.perStorePrice > b.perStorePrice;
}

/**
 * 贪心算法，月饼题目
 */
int main() {
     int moonTypes = 0, maxCommand = 0;
    scanf("%d%d", &moonTypes, &maxCommand);

    for (int i = 0; i < moonTypes; ++i) {
        scanf("%lf", &mooncake[i].store);
    }

    for (int i = 0; i < moonTypes; ++i) {
        scanf("%lf", &mooncake[i].saleprice);
        mooncake[i].perStorePrice = mooncake[i].saleprice / mooncake[i].store;
    }

    sort(mooncake, mooncake + moonTypes, cmpMoon);
    double sum = 0;
    int remainingCommand = maxCommand;
    for (int i = 0; i < moonTypes; ++i) {
        if (remainingCommand <= mooncake[i].store) {
            sum += remainingCommand * mooncake[i].perStorePrice;
            printf("%.2f", sum);
            break;
        } else {
            sum += mooncake[i].saleprice;
            remainingCommand = remainingCommand - mooncake[i].store;
            if (i == moonTypes - 1) {
                printf("%.2f", sum);
                break;
            }
        }
    }
    return 0;
}

PAT B1023

#include <stdio.h>

int minNumber[50] = {};

int main(){
    int numCount[10] = {0};
    //总字符个数
    int sum = 0;
    bool initialflag = false;
    for (int i = 0; i < 10; ++i) {
        scanf("%d", &numCount[i]);
        if (numCount[i] > 0) {
            sum += numCount[i];
        }

        //找到非0的第一个首位
        if (i >= 1 && numCount[i] > 0 && !initialflag) {
            minNumber[0] = i;
            numCount[i] = numCount[i] - 1;
            initialflag = true;
        }
    }

    //遍历，拼接字符
    int minTotalCode = 1;
    for (int i = 0; i < 10; ++i) {
        if (numCount[i] != 0) {
            for (int j = 0; j < numCount[i]; ++j) {
                minNumber[minTotalCode] = i;
                minTotalCode++;
            }
        }
    }

    for (int i = 0; i < sum; ++i) {
        printf("%d", minNumber[i]);
    }
    return 0;
}