84 lines
2.1 KiB
C++
84 lines
2.1 KiB
C++
#include <stdio.h>
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#define RISING true
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#define FALLING false
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unsigned long long totalCount;
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int peakValleyPos[10000];
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int powers[100000];
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void find_pairs(int startPeakNum, int endPeakNum) {
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if (startPeakNum + 2 == endPeakNum) {
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totalCount +=
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(peakValleyPos[endPeakNum] - peakValleyPos[startPeakNum + 1]) *
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(peakValleyPos[startPeakNum + 1] - peakValleyPos[startPeakNum]) - 1;
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return;
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}
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int maxInsidePeak = startPeakNum + 2;
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int i = maxInsidePeak + 2;
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while (i < endPeakNum) {
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if (powers[i] > powers[peakValleyPos[maxInsidePeak]]) {
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maxInsidePeak = i;
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}
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i += 2;
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}
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int countLeft = 0, countRight = 0;
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i = startPeakNum;
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while (powers[i] >= powers[peakValleyPos[maxInsidePeak]]) {
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countLeft++;
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i++;
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}
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i = endPeakNum;
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while (peakValleyPos[i] >= powers[peakValleyPos[maxInsidePeak]]) {
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countRight++;
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i--;
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}
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totalCount += countLeft * countRight;
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find_pairs(startPeakNum, maxInsidePeak);
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find_pairs(maxInsidePeak, endPeakNum);
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}
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int main() {
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int N;
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int newPeakValleyPosIndex = 1;
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bool direction = FALLING;
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int firstPeakPos = 0, lastPeakPos = 0;
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peakValleyPos[0] = 0;
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scanf("%d", &N);
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scanf("%d", &powers[0]);
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scanf("%d", &powers[1]);
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if (powers[0] < powers[1]) {
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direction = RISING;
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firstPeakPos = 1;
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}
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for (int i = 2; i < N; i++) {
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scanf("%d", &powers[i]);
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if (powers[i] > powers[i - 1] && direction == FALLING) {
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peakValleyPos[newPeakValleyPosIndex++] = i - 1;
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direction = RISING;
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}
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else if (powers[i] < powers[i - 1] && direction == RISING) {
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peakValleyPos[newPeakValleyPosIndex++] = i - 1;
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direction = FALLING;
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}
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}
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if (direction == RISING) {
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peakValleyPos[newPeakValleyPosIndex] = N - 1;
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lastPeakPos = newPeakValleyPosIndex;
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}
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else {
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lastPeakPos = newPeakValleyPosIndex - 1;
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}
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find_pairs(firstPeakPos, lastPeakPos);
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totalCount += N - 1;
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printf("%lld", totalCount);
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} |