在O（1）的時間內(nèi)計算n個整數(shù)落在區(qū)間[a,b]的個數(shù)

預(yù)處理時間為O（n+k)
算法導(dǎo)論第三版8.2-4題

int find_inverter_count(int *array,int length,int maximum,int inverter_left,int inverter_right) {if(inverter_left<0 || inverter_right>maximum || inverter_right<inverter_left){perror("inverter error");return -1;}int *count_array = new int[maximum+1];for (int i = 0; i < maximum+1; ++i) {count_array[i] = 0;}for (int i = 0; i < length; ++i) {count_array[array[i]] = count_array[array[i]] + 1;}for (int i = 1; i < maximum+1; ++i) {count_array[i] = count_array[i] + count_array[i-1];}int count = 0;if(inverter_left == 0)count = count_array[inverter_right];elsecount = count_array[inverter_right] - count_array[inverter_left - 1];delete [] count_array;return count; } 創(chuàng)作挑戰(zhàn)賽新人創(chuàng)作獎勵來咯，堅持創(chuàng)作打卡瓜分現(xiàn)金大獎

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