partial sort.

first use std::nth_element to find pivot,

then use std::stable_partition with the pivot to partition the largest k, whose indices are in acsending order, print them in reverse order.

p.s. lambda expression is also used.

STL is powerful.

#include <cstdio>

#include <vector>

#include <algorithm>

struct IRPair{

    int ind;

    double rate;

};

int main() {

    //freopen("input.txt","r",stdin);

    int num_people, num_candidate, num_final, i,j;

    double tmp;

    std::vector<IRPair> vec;

    std::vector<double> ratings;

    while(scanf("%d%d%d",&num_people,&num_candidate,&num_final)!=EOF) {

        vec.resize(num_candidate);

        ratings.clear(); ratings.resize(num_candidate);

        for(i=0;i<num_people;++i)

        for(j=0;j<num_candidate;++j) { scanf("%lf",&tmp); ratings[j]+=tmp; }

        for(i=0;i<num_candidate;++i) { vec[i].ind=i+1; vec[i].rate=ratings[i]; }

        std::nth_element(&ratings[0],&ratings[num_candidate-num_final],&ratings[num_candidate]);

        tmp=ratings[num_candidate-num_final];

        std::stable_partition(&vec[0],&vec[num_candidate],[tmp](const IRPair &x) { return x.rate>=tmp; });

        for(i=num_final-1;i>0;--i) { printf("%d ",vec[i].ind);}

        printf("%d\n",vec[0].ind);

    }

    return 0;

}

156 ms for double, vector

140 ms for float, vector

140 ms for double, array

124 ms for float, arry

time for array / time for vector = 90%

版权声明：本文为博主原创文章，未经博主允许不得转载。// p.s. If in any way improment can be achieved, better performance or whatever, it will be well-appreciated to let me know, thanks in advance.