排序並記錄排序前的索引（類似matlab sort函數）

這裡用到vector比較方便。

#include<iostream>

#include<vector>

#include<algorithm>

using namespace std;

struct num_label {

int num;

int label;

};

//自定義「大於」

bool comp(const num_label &a, const num_label &b) {

return a.num > b.num;

}

bool comp2(const num_label &a, const num_label &b) {

return a.num < b.num;

}

int main()

{

vector<num_label> vectorNumLabel(5);

vectorNumLabel[0].num = 78 ;

vectorNumLabel[0].label = 0;

vectorNumLabel[1].num = 49;

vectorNumLabel[1].label = 1;

vectorNumLabel[2].num = 300;

vectorNumLabel[2].label = 2;

vectorNumLabel[3].num = 40;

vectorNumLabel[3].label = 3;

vectorNumLabel[4].num = 550;

vectorNumLabel[4].label = 4;

cout << "===========排序前================" << endl;

for (vector<num_label>::iterator it = vectorNumLabel.begin(); it != vectorNumLabel.end(); it++) {

cout << "num: " << it->num << " label: " << it->label << endl;

}

cout << endl;

cout << endl;

cout << endl;

sort(vectorNumLabel.begin(), vectorNumLabel.end(), comp);

cout << "===========排序後,由大到小================" << endl;

for (vector<num_label>::iterator it = vectorNumLabel.begin(); it != vectorNumLabel.end(); it++) {

cout << "num: " << it->num << " label: " << it->label << endl;

}

cout << endl;

cout << endl;

cout << endl;

sort(vectorNumLabel.begin(), vectorNumLabel.end(), comp2);

cout << "===========排序後,由小到大================" << endl;

for (vector<num_label>::iterator it = vectorNumLabel.begin(); it != vectorNumLabel.end(); it++) {

cout << "num: " << it->num << " label: " << it->label << endl;

}

system("pause");

return 0;

}

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